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Effects of elevated CO2 on the protein concentration of food crops: a meta-analysis

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Abstract

Meta-analysis techniques were used to examine the effect of elevated atmospheric carbon dioxide [CO2] on the protein concentrations of major food crops, incorporating 228 experimental observations on barley, rice, wheat, soybean and potato. Each crop had lower protein concentrations when grown at elevated (540–958 μmol mol−1) compared with ambient (315–400 μmol mol−1) CO2. For wheat, barley and rice, the reduction in grain protein concentration was ∼10–15% of the value at ambient CO2. For potato, the reduction in tuber protein concentration was 14%. For soybean, there was a much smaller, although statistically significant reduction of protein concentration of 1.4%. The magnitude of the CO2 effect on wheat grains was smaller under high soil N conditions than under low soil N. Protein concentrations in potato tubers were reduced more for plants grown at high than at low concentrations of ozone. For soybean, the ozone effect was the reverse, as elevated CO2 increased the protein concentration of soybean grown at high ozone concentrations. The magnitude of the CO2 effect also varied depending on experimental methodology. For both wheat and soybean, studies performed in open-top chambers produced a larger CO2 effect than those performed using other types of experimental facilities. There was also indication of a possible pot artifact as, for both wheat and soybean, studies performed in open-top chambers showed a significantly greater CO2 effect when plants were rooted in pots rather than in the ground. Studies on wheat also showed a greater CO2 effect when protein concentration was measured in whole grains rather than flour. While the magnitude of the effect of elevated CO2 varied depending on the experimental procedures, a reduction in protein concentration was consistently found for most crops. These findings suggest that the increasing CO2 concentrations of the 21st century are likely to decrease the protein concentration of many human plant foods.

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... However, to the best of our knowledge, there has been no investigation of changes in leaf N allocation in woody plants under different N availability conditions under eCO 2 conditions. In contrast, N reduction also occurs in other sink organs apart from leaves [19][20][21]. For example, the N concentration in the edible parts of major food crops decreased by 9%-15% [20], whereas that aboveground in wheat decreased by 23% [21]. ...
... In contrast, N reduction also occurs in other sink organs apart from leaves [19][20][21]. For example, the N concentration in the edible parts of major food crops decreased by 9%-15% [20], whereas that aboveground in wheat decreased by 23% [21]. N reduction in sink organs can be regarded as a dilution of NSC accumulation [19]. ...
... In roots, starch (9.8%) concentration significantly increased under elevated CO 2 conditions, whereas soluble sugar concentration decreased by 6.7% but not significantly [22]. The effect of eCO 2 on leaf N dilution can be reduced by N fertilization [20,23]; thus, it can be speculated whether NSC changes can be attributed to N concentration variations in other sink organs under different CO 2 and N conditions. ...
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(1) Background: Down-regulation of photosynthesis has been commonly reported in elevated CO2 (eCO2) experiments and is accompanied by a reduction of leaf nitrogen (N) concentration. Decreased N concentrations in plant tissues under eCO2 can be attributed to an increase in nonstructural carbohydrate (NSC) and are possibly related to N availability. (2) Methods: To examine whether the reduction of leaf N concentration under eCO2 is related to N availability, we investigated understory Fraxinus rhynchophylla seedlings grown under three different CO2 conditions (ambient, 400 ppm [aCO2]; ambient × 1.4, 560 ppm [eCO21.4]; and ambient × 1.8, 720 ppm [eCO21.8]) and three different N concentrations for 2 years. (3) Results: Leaf and stem biomass did not change under eCO2 conditions, whereas leaf production and stem and branch biomass were increased by N fertilization. Unlike biomass, the light-saturated photosynthetic rate and photosynthetic N-use efficiency (PNUE) increased under eCO2 conditions. However, leaf N, Rubisco, and chlorophyll decreased under eCO2 conditions in both N-fertilized and unfertilized treatments. Contrary to the previous studies, leaf NSC decreased under eCO2 conditions. Unlike leaf N concentration, N concentration of the stem under eCO2 conditions was higher than that under ambient CO2 (4). Conclusions: Leaf N concentration was not reduced by NSC under eCO2 conditions in the understory, and unlike other organs, leaf N concentration might be reduced due to increased PNUE.
... Some others have forecasted that the negative impacts of climate change on crop productivity would be more severe under more intense warming scenarios, with a median yield loss near 15% in the most intense warming scenarios [16]. Moreover, the quality of agricultural products, for example, protein content, would likely decrease and susceptibility to insect pests increase under increased CO 2 fertilization [17,18]. As a result, against the background of global warming, the derived precipitation changes, pest and disease outbreaks, and increasing population would aggravate global food insecurity [7,15,19]. ...
... Some others have forecasted that the negative impacts of climate change on crop productivity would be more severe under more intense warming scenarios, with a median yield loss near 15% in the most intense warming scenarios [16]. Moreover, the quality of agricultural products, for example, protein content, would likely decrease and susceptibility to insect pests increase under increased CO2 fertilization [17,18]. As a result, against the background of global warming, the derived precipitation changes, pest and disease outbreaks, and increasing population would aggravate global food insecurity [7,15,19]. ...
... As a consequence of sealed experiment conditions, the compensation effect of elevated CO 2 was overestimated in OTC or EC conditions whereas it was more authentic in FACE [32,33]. Some others reported that FACE differs from reality because CO 2 input in FACE is stable [17,34]. Some studies also indicated that all these facilities were fundamentally the same [24,35]. ...
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Global food insecurity is becoming more severe under the threat of rising global carbon dioxide concentrations, increasing population, and shrinking farmlands and their degeneration. We acquired the ISI Web of Science platform for over 31 years (1988–2018) to review the research on how climate change impacts global food security, and then performed cluster analysis and research hotspot analysis with VosViewer software. We found there were two drawbacks that exist in the current research. Firstly, current field research data were defective because they were collected from various facilities and were hard to integrate. The other drawback is the representativeness of field research site selection as most studies were carried out in developed countries and very few in developing countries. Therefore, more attention should be paid to developing countries, especially some African and Asian countries. At the same time, new modified mathematical models should be utilized to process and integrate the data from various facilities and regions. Finally, we suggested that governments and organizations across the world should be united to wrestle with the impact of climate change on food security.
... The earliest acknowledgement of [CO 2 ] on nutritional aspects are by Sionit [3,4], reporting that leaves growing in elevated [CO 2 ] had higher carbohydrate levels, higher C:N ratios and lower leaf nitrogen. These observations have gained credence over time, including multiple meta-analyses [5][6][7][8][9][10]. Currently, there is extensive evidence from multiple studies and meta-analyses that increasing [CO 2 ] will reduce protein and mineral concentrations from a wide-variety of plant-based food sources, with substantial global consequences for human and animal nutrition. ...
... With respect to staple crops, a meta-analysis of 228 observations on barley, potato, rice and wheat reported reductions in protein concentrations that ranged from ca −10 to −15% [6]. A more extensive meta-analysis of 7761 pairs of observations over 130 species and cultivars reported an average 8% decline in mineral concentrations, excepting Mn [7]. ...
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While the role of CO2 as a greenhouse gas in the context of global warming is widely acknowledged, additional data from multiple sources is demonstrating that rising CO2 of and by itself will have a tremendous effect on plant biology. This effect is widely recognized for its role in stimulating photosynthesis and growth for multiple plant species, including crops. However, CO2 is also likely to alter plant chemistry in ways that will denigrate plant nutrition. That role is also of tremendous importance, not only from a human health viewpoint, but also from a global food–web perspective. Here, the goal is to review the current evidence, propose potential mechanistic explanations, provide an overview of critical unknowns and to elucidate a series of next steps that can address what is, overall, a critical but unappreciated aspect of anthropogenic climate change.
... Mukherjee (2012) [11] reported higher gross return, net return and B: C with early sowing as compared to late sown crops. Taub et al. (2008) [20] reported that in the grain crops wheat, the reduction in protein mediated by elevated [CO 2 ] was reported to be 10%. Shortening of the critical phenological period, as a key factor in determining the photoperiod and productivity of crops, may further explain the poor performance under delayed sowing (Ferrise et al., 2010;Sattar et al., 2010) [5,15] . ...
... Mukherjee (2012) [11] reported higher gross return, net return and B: C with early sowing as compared to late sown crops. Taub et al. (2008) [20] reported that in the grain crops wheat, the reduction in protein mediated by elevated [CO 2 ] was reported to be 10%. Shortening of the critical phenological period, as a key factor in determining the photoperiod and productivity of crops, may further explain the poor performance under delayed sowing (Ferrise et al., 2010;Sattar et al., 2010) [5,15] . ...
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A field experiment was conducted to assess the effect of sowing dates and varieties on the nutrient uptake and economics of Wheat crop (Triticum aestivum L.) under the changing climate in Rabi season (November-April) 2017-18. The experiment was conducted at Crop Research Station Masodha, Narendra Deva University of Agriculture and Technology, Kumarganj, Ayodhaya (U.P) during Rabi season. The experiment was carried out for four dates of sowing (05th November, 25th November, 15th December, 05th January) in the main plot against six varieties (HD-3086, HS-562, HI-1544, WR-544, MACS-6222, and HD-2967) in the subplot with three replication. Available nitrogen (195.3) and phosphorus (17.25) is low and potassium (285.0) is found medium in the soil. The soil was found silty loam having neutral pH and organic carbon with a value of 0.35, EC (0.25). The soil was moderate for the cultivation of the wheat crop. The present study was taken to generate information about the effect of different sowing dates and varieties on the growth of the Wheat crop. The optimum dates of sowing are evaluated in this experiment because of the increase in seasonal temperature. Among the varieties, HD-3086 on 25th November provides the best results. Protein content in grain, and nitrogen, phosphorus and potassium content of grain and straw as well as their uptake by grain and straw was significantly higher with sowing of HD-3086 on 25th November. Maximum net return was found with sowing of HD-3086 on 25th November.
... Mukherjee (2012) [11] reported higher gross return, net return and B: C with early sowing as compared to late sown crops. Taub et al. (2008) [20] reported that in the grain crops wheat, the reduction in protein mediated by elevated [CO 2 ] was reported to be 10%. Shortening of the critical phenological period, as a key factor in determining the photoperiod and productivity of crops, may further explain the poor performance under delayed sowing (Ferrise et al., 2010;Sattar et al., 2010) [5,15] . ...
... Mukherjee (2012) [11] reported higher gross return, net return and B: C with early sowing as compared to late sown crops. Taub et al. (2008) [20] reported that in the grain crops wheat, the reduction in protein mediated by elevated [CO 2 ] was reported to be 10%. Shortening of the critical phenological period, as a key factor in determining the photoperiod and productivity of crops, may further explain the poor performance under delayed sowing (Ferrise et al., 2010;Sattar et al., 2010) [5,15] . ...
Research
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A field experiment was conducted to assess the effect of sowing dates and varieties on the nutrient uptake and economics of Wheat crop (Triticum aestivum L.) under the changing climate in Rabi season (November-April) 2017-18. The experiment was conducted at Crop Research Station Masodha, Narendra Deva University of Agriculture and Technology, Kumarganj, Ayodhaya (U.P) during Rabi season. The experiment was carried out for four dates of sowing (05 th November, 25 th November, 15 th December, 05 th January) in the main plot against six varieties (HD-3086, HS-562, HI-1544, WR-544, MACS-6222, and HD-2967) in the subplot with three replication. Available nitrogen (195.3) and phosphorus (17.25) is low and potassium (285.0) is found medium in the soil. The soil was found silty loam having neutral pH and organic carbon with a value of 0.35, EC (0.25). The soil was moderate for the cultivation of the wheat crop. The present study was taken to generate information about the effect of different sowing dates and varieties on the growth of the Wheat crop. The optimum dates of sowing are evaluated in this experiment because of the increase in seasonal temperature. Among the varieties, HD-3086 on 25 th November provides the best results. Protein content in grain, and nitrogen, phosphorus and potassium content of grain and straw as well as their uptake by grain and straw was significantly higher with sowing of HD-3086 on 25 th November. Maximum net return was found with sowing of HD-3086 on 25 th November.
... In FACE experiments embracing more than 100 barley genotypes, Ingvordsen et al. (2015Ingvordsen et al. ( , 2016 observed an average grain yield increase of 17%. Similar magnitude of yield increase for barley was reported in a meta-analysis by Taub et al. (2008). Effects of elevated CO 2 depend on the intensity of other growth factors, in particular N and water, where limitations will reduce yield responses (Kimball, 2016). ...
... The applied light intensity of 400-500 μmol m À2 s À1 should be sufficient to analyze the effect of high CO 2 in barley (Kromer et al., 1993). The plants were grown in relatively small pots containing 2 L soil and the volume of the rooting medium has in some cases , but not in others (Taub et al., 2008) been found to affect the response to CO 2 . Any effect of pot size must be assumed strongly confounded with nutrient supply. ...
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Increasing atmospheric CO2 concentration is expected to enhance the grain yield of C3 cereal plants, while at the same time reducing the concentrations of minerals and proteins. This will lead to a lower nutritional quality and increase global problems associated with micronutrient malnutrition. Among the barley grain storage proteins, the C-hordein fraction has the lowest abundance of sulphur (S) containing amino acids and is poorest in binding of zinc (Zn). In the present study, C-hordein-suppressed barley lines with reduced C-hordein content, obtained by use of antisense or RNAi technology, were investigated under ambient and elevated atmospheric CO2 concentration. Grains of the C-hordein-suppressed lines showed 50% increase in the concentrations of Zn and iron (Fe) in the core endosperm relative to the wild-type under both ambient and elevated atmospheric CO2. Element distribution images obtained using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) confirmed the enrichment of Fe and Zn in the core endosperm of the lines with modified storage protein composition. We conclude that modification of grain storage proteins may improve the nutritional value of cereal grain with respect to Zn and Fe under both normal and future conditions of elevated atmospheric CO2.
... Climate change may affect human health by altering the food nutrient content via increasing concentrations of CO 2 in the atmosphere (Dietterich et al., 2015). Elevated CO 2 results in more rapid growth rates but also reduces plant protein content and micronutrients such as calcium, iron, and zinc (Taub et al., 2008;Taub, 2010;Fernando et al., 2012;Loladze, 2014;Myers et al., 2014;Ziska and McConnell, 2016;Medek et al., 2017;Myers, 2017;Smith et al., 2017;Uddling et al., 2018). Most crops grown under elevated CO 2 -except for legumes and C4 cropssystematically exhibit decreased concentrations of nitrogen and protein in the edible portion (Cotrufo et al., 1998;Pleijel et al., 1999;Idso and Idso, 2001;Jablonski et al., 2002). ...
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Many consequences of climate change undermine the stability of global food systems, decreasing food security and diet quality, and exposing vulnerable populations to multiple forms of malnutrition. The emergence of pandemics such as Covid-19 exacerbate the situation and make interactions even more complex. Climate change impacts food systems at different levels, including changes in soil fertility and crop yield, composition, and bioavailability of nutrients in foods, pest resistance, and risk of malnutrition. Sustainable and resilient food systems, coupled with climate-smart agriculture, are needed to ensure sustainable diets that are adequately diverse, nutritious, and better aligned with contextual ecosystem functions and environmental conservation. Robust tools and indicators are urgently needed to measure the reciprocal food systems-climate change interaction, that is further complicated by pandemics, and how it impacts human health.
... This is largely due to the impact of climate change on food systems (Table 2). Food quality will continue to be strongly impacted by climate change (Taub et al., 2008;Tirado et al., 2010), and will result in reduced caloric indices (Havlík et al., 2014;Ray et al., 2019). Strengthening climate services in agriculture to ensure resilience to climate change is imperative if better food security indices are to be achieved. ...
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Food security in Nigeria is presently in dire strait owing to several factors, such as skyrocketing energy prices, climate change, and terrorism. This study is aimed at revealing the role of the aforementioned factors in shaping food affordability and availability in the country. The study used descriptive statistics and coefficients of variation and determination to ascertain the change in the trend in these factors and their correlates to food security over time. From the results of our research team, we inferred that temperature increases, political instability, rising food prices and erratic energy supply have had distressing consequences in the areas of affordability, availability and stability of food supplies. We conclude that a rapidly growing population such as Nigeria's would need crucial interventions in increasing food production, mitigating the impacts of climate change, and buffering energy supplies. Ultimately, Nigeria needs to overhaul the important components of her food systems and the respective linkages between these components in order to ensure food security for the entire population.
... Hence, people may be exposed to consuming toxic food or may not be able to get the recommended quantity of daily calorie Food and human security in Nigeria intake due to decrease in crop quality. Taub et al. (2018) conducted a meta-analysis of different experiments on the effect of climate change on food production and found that the exposition of crops to high CO 2 concentration reduced the protein concentration in crops. Hence, as CO 2 concentration in the atmosphere continues to increase, the quality of food crops will gradually be decreasing. ...
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Purpose The purpose of this study is to unravel the changing nature of climate change impact on the food and human security sector of the Nigerian State. Design/methodology/approach This study is an in-depth case study that involves the use of both quantitative and qualitative data. Statistical data on climate variability in Nigeria obtained from reliable databases were use in the making of analysis. Also, data derived from semi-structure interviews and special reports from International Non-governmental organizations on the subject matter were also used in the study. The findings of the study were based on an in-depth analysis of both primary and secondary sources of data. The secondary data were derived from existing published academic works. The primary data was developed using qualitative data that were collected from January to November, 2018 to 2019 in the different regions of Nigeria. For the South East, primary data was collected from Abakaliki, Ebonyi State. In the South-South, primary data was collected from Asaba, Delta State. In the South West, primary data was collected from Barutin, Kwara State. In the North East, primary data was collected from Maiduguri, while in North West, data was collected from Gusau, Zamfara State. In the North Central, data was collected from Markurdi, Benue State. During the data collection, 48 semi-structured Key Informant Interviews (KIIs) were carried out in the six selected research areas that represented their geo-political zones. Six Focus Group Discussions (FGDs) were carried out, one for each of these six selected cities. Each of the Focus Group Discussions comprised between five and seven respondents. The idea of KIIs and FGDs is to allow the respondents to freely express their ideas comprehensively. Again, in other to get varied forms of responses, the respondents are mainly farmers however, a number of NGOs, civil servants, fertilizer sellers, government officials, transporters and aged men and women/retirees. It should be noted that the respondents cut across male and female gender of all ages and ethnic configuration. The respondents were also randomly selected through social networking. To avoid having people of similar The KIIs were three academics; two community leaders; two small scale fish farmers; rice, cassava, fish, livestock and crop farmers. All KIIs ad TIs were transcribed and analysed using thematic content analysis. Findings The findings revealed that climate change has negatively affected food security in Nigeria. it has also led to continuous armed confrontations over natural resources thereby undermining human security in the country. Originality/value This study is 100% original and can be assessed through turn it in evaluation.
... In the present study, the rice protein concentration (PC) decreased by about 5% under eCO 2 across the three seasons, which is in agreement with previous studies (Yang et al., 2007;Myers et al., 2014;Zhang et al., 2015); this phenomenon was not affected by CO 2 fumigation (Taub et al., 2008). Zhu et al. (2018) cultivated 18 rice varieties of a wide genotypic and phenotypic range and found that the PC of all varieties showed a decreasing trend under FACE eCO 2 treatment; the average decrease value was twice that of our study. ...
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Evaluating the impact of increasing CO 2 on rice quality is becoming a global concern. However, whether adjusting the source-sink ratio will affect the response of rice grain quality to elevated CO 2 concentrations remains unknown. In 2016–2018, we conducted a free-air CO 2 enrichment experiment using a popular japonica cultivar grown at ambient and elevated CO 2 levels (eCO 2 , increased by 200 ppm), reducing the source-sink ratio via cutting leaves (LC) at the heading stage, to investigate the effects of eCO 2 and LC and their interactions on rice processing, appearance, nutrition, and eating quality. Averaged across 3 years, eCO 2 significantly decreased brown rice percentage (−0.5%), milled rice percentage (−2.1%), and head rice percentage (−4.2%) but increased chalky grain percentage (+ 22.3%) and chalkiness degree (+ 26.3%). Markedly, eCO 2 increased peak viscosity (+ 2.9%) and minimum viscosity (+ 3.8%) but decreased setback (−96.1%) of powder rice and increased the appearance (+ 4.5%), stickiness (+ 3.5%) and balance degree (+ 4.8%) of cooked rice, while decreasing the hardness (−6.7%), resulting in better palatability (+ 4.0%). Further, eCO 2 significantly decreased the concentrations of protein, Ca, S, and Cu by 5.3, 4.7, 2.2, and 9.6%, respectively, but increased K concentration by 3.9%. Responses of nutritional quality in different grain positions (brown and milled rice) to eCO 2 showed the same trend. Compared with control treatment, LC significantly increased chalky grain percentage, chalkiness degree, protein concentration, mineral element levels (except for B and Mn), and phytic acid concentration. Our results indicate that eCO 2 reduced rice processing suitability, appearance, and nutritional quality but improved the eating quality. Rice quality varied significantly among years; however, few CO 2 by year, CO 2 by LC, or CO 2 by grain position interactions were detected, indicating that the effects of eCO 2 on rice quality varied little with the growing seasons, the decrease in the source-sink ratios or the different grain positions.
... However, a study showed that the more closely fumigation conditions mimicked field conditions, the smaller was the stimulation of yield by elevated [CO 2 ] (Ainsworth and Long, 2005). Additionally, some plants may begin to develop an adverse response to enriched CO 2 environments, when beyond certain CO 2 concentration limits (Cotrufo et al., 1998;Long et al., 2006;Taub et al., 2008;Xu, 2015). Meanwhile, the response of plant gas exchange to e[CO 2 ] may be limited by other abiotic factors, such as high-temperature stress, low N/P, and low water availability (Bajji et al., 2001;Hessini et al., 2009;Zhao et al., 2016;Gorthi et al., 2019;Jiang et al., 2020). ...
Article
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Elevated atmospheric CO 2 concentrations ([eCO 2 ]) and soil water deficits significantly influence gas exchange in plant leaves, affecting the carbon-water cycle in terrestrial ecosystems. However, it remains unclear how the soil water deficit modulates the plant CO 2 fertilization effect, especially for gas exchange and leaf-level water use efficiency (WUE). Here, we synthesized a comprehensive dataset including 554 observations from 54 individual studies and quantified the responses for leaf gas exchange induced by e[CO 2 ] under water deficit. Moreover, we investigated the contribution of plant net photosynthesis rate ( P n ) and transpiration rates ( T r ) toward WUE in water deficit conditions and e[CO 2 ] using graphical vector analysis (GVA). In summary, e[CO 2 ] significantly increased P n and WUE by 11.9 and 29.3% under well-watered conditions, respectively, whereas the interaction of water deficit and e[CO 2 ] slightly decreased P n by 8.3%. Plants grown under light in an open environment were stimulated to a greater degree compared with plants grown under a lamp in a closed environment. Meanwhile, water deficit reduced P n by 40.5 and 37.8%, while increasing WUE by 24.5 and 21.5% under ambient CO 2 concentration (a[CO 2 ]) and e[CO 2 ], respectively. The e[CO 2 ]-induced stimulation of WUE was attributed to the common effect of P n and T r , whereas a water deficit induced increase in WUE was linked to the decrease in T r . These results suggested that water deficit lowered the stimulation of e[CO 2 ] induced in plants. Therefore, fumigation conditions that closely mimic field conditions and multi-factorial experiments such as water availability are needed to predict the response of plants to future climate change.
... Higher levels of carbon dioxide make carbon more available, but plants also need other nutrients like nitrogen, phosphorus, to grow and survive, less of these nutrients as well will cause the nutritional quality of many plants to decrease. In different experiments with elevated carbon dioxide levels, protein concentrations in wheat, rice, barley, and potato tubers, decreased by 5-14% (Taub et al., 2008). ...
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In the study of the environmental effect of biogas production, it is essential to identify the main constituents of the biogas with a special interest biogas process system. This paper reviews the formation processes of biogas production. In this paper, the roles of biogas application were discussed to make them more suitable to the environment and human activities. Furthermore, questions related to the disposal and management of wastes which leads to serious environmental and global concerns were addressed. Although these wastes offer abundant resources: large proportions of the wastes are biodegradable materials and can be efficiently used in producing biogas, which can serve as an answer to the greenhouse gas problem but also inappropriate controlling of the wastes will lead to the rise of greenhouse gas in the environment.
... Ezzel az értékkel elmarad más gabo naféléhez képest. Táplálóanyag paramétereinek fontos szabályozó tényezője a meteorológiai tényező (Izsáki 2007, Hegyi et al. 2008, Franklin et al. 2010, Butts-Wilmsmeyer et al. 2019, továbbá a talaj termékenysége (Major et al. 2010), a trágyázás (Triboi et al. 2000, Taub et al. 2008, Karasu 2012, Riedell 2014) és a genotípus (Hegyi et al. 2007, Kim et al. 2001, Guo et al. 2013. ...
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A vetésidő, az időjárás és a kukoricaszem fehérje-és olajtartalma közötti kapcsolat eltérő genotípusú kukorica hibrideknél 1 SZÉLES ADRIENN-1 HORVÁTH ÉVA-2 HUZSVAI LÁSZLÓ Debreceni Egyetem 1 Mezőgazdaság-, Élelmiszertudományi és Környezetgazdálkodási Kar, Földhasznosítási, Műszaki és Területfejlesztési Intézet, Debrecen 2 Gazdaságtudományi Kar, Statisztika és Módszertani Intézet, Debrecen Összefoglalás A tanulmány az állati takarmányozásra szánt kukorica hibridek minőségi paramé terei-re, valamint a vetésidő és időjárási tényező hatásának értékelésére irányult. A vizsgá-la tokat a Debreceni Egyetem Kísérleti Telep (47°33' É, 21°26' K, 111 m), mészlepedékes cser nozjom talaján, 2011-2013 év között végeztük. Három vetésidő (VD) és három ugyan azon kukorica hibrid (FAO 290, FAO 350 és FAO 420) bevonásával, természetes csa padékellátottság mellett. A hároméves eredmény azt mutatta, hogy a VD1 és VD2 vetés tenyészidőszakában magasabb a kumulatív növekedési foknap (GDD) érték, azon ban a növény fejlődésének korai stádiumában fellépő alacsony hőmérséklet csökkenti a kukoricaszem fehérje-és olajtartalmát. Így a VD késleltetésével (VD3), ahol a napi hőmérséklet már magasabb, azonban alacsonyabb a tenyészidőszak kumulatív GDD értéke a kukoricaszem fehérjetartalma 12,5%-kal, az olajtartalma 12,8%-kal emel-kedett (P<0,05; P<0,05). Összességében a legnagyobb kumulatív GDD értékkel és a te-nyészidőben lehullott mindössze 277 mm csapadékmennyiséggel rendelkező évben (2012) volt-a hibridek és a VD átlagában-a fehérjetartalom a legnagyobb (10,5 g/ 100 g sza.; P<0,05), míg az olajtartalom a legalacsonyabb (4,6 g/100 g sza.; P<0,05). A hib ridek fehérjetartalma az évek átlagában a-FAO 350 kivételével (VD2)-VD3 vetés
... In June of 2021 [1] global CO 2 concentrations were 418.7 ppm, but these are predicted to double by the end of this century [2] Elevated CO 2 (eCO 2 ) is known to affect plant growth, crop yield and nutritional status of agricultural products. Although it seems to induce higher growth and yield [3][4][5][6][7][8][9] a number of studies making use of meta-analysis methodologies showed reduced mineral or protein concentrations in several crop species such as wheat, barley, rice, common bean, soybean, among others [10][11][12][13][14]. In previous studies, eCO 2 has been reported to induce photosynthesis [15], stomatal closure [2,16,17] and increase the levels of leaf organic acids concentrations [18][19][20]. ...
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Elevated CO2 (eCO2) has been reported to cause mineral losses in several important food crops such as soybean (Glycine max L.) and common bean (Phaseolus vulgaris L.). In addition, more than 30% of the world’s arable land is calcareous, leading to iron (Fe) deficiency chlorosis and lower Fe levels in plant tissues. We hypothesize that there will be combinatorial effects of eCO2 and Fe deficiency on the mineral dynamics of these crops at a morphological, biochemical and physiological level. To test this hypothesis, plants were grown hydroponically under Fe sufficiency (20 μM Fe-EDDHA) or deficiency (0 μM Fe-EDDHA) at ambient CO2 (aCO2, 400 ppm) or eCO2 (800 ppm). Plants of both species exposed to eCO2 and Fe deficiency showed the lowest biomass accumulation and the lowest root: shoot ratio. Soybean at eCO2 had significantly higher chlorophyll levels (81%, p < 0.0001) and common bean had significantly higher photosynthetic rates (60%, p < 0.05) but only under Fe sufficiency. In addition, eCO2 increased ferric chelate reductase acivity (FCR) in Fe-sufficient soybean by 4-fold (p < 0.1) and in Fe-deficient common bean plants by 10-fold (p < 0.0001). In common bean, an interactive effect of both environmental factors was observed, resulting in the lowest root Fe levels. The lowering of Fe accumulation in both crops under eCO2 may be linked to the low root citrate accumulation in these plants when grown with unrestricted Fe supply. No changes were observed for malate in soybean, but in common bean, shoot levels were significantly lower under Fe deficiency (77%, p < 0.05) and Fe sufficiency (98%, p < 0.001). These results suggest that the mechanisms involved in reduced Fe accumulation caused by eCO2 and Fe deficiency may not be independent, and an interaction of these factors may lead to further reduced Fe levels.
... More field data should be collected to reduce uncertainties in estimating the response of regional wheat nutritional quality to climate. Alternatively, a decrease in wheat PC due to the negative effects of elevated atmospheric carbon dioxide ([CO 2 ]) has been widely reported from field experiments on free-air carbon dioxide enrichment (Taub et al 2008). We did not consider the direct effects of [CO 2 ] on PC variability, in part due to the limitation of statistical models, and in part due to the slight increase of global annual mean [CO 2 ] from 381 ppm in 2006 relative to 408 ppm in 2018 (www.esrl.noaa.gov/gmd/ ...
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Climate change effects on global food security are not only limited to its effects on the yield of cereals but also their nutritional quality. However, climate change effects on crop nutritional quality, particularly grain protein concentration (PC) on a large geographical scale have not yet been quantified in China. For this purpose, we assessed the effects of three key climatic factors (temperature, precipitation, and solar radiation) on wheat PC in ten wheat-growing areas of China using a series of statistical models on a county-level PC dataset. The results demonstrated that the average PC in China from 2006 to 2018 ranged from 12.01% to 14.50% across the ten areas, with an obvious spatial difference pattern showing an increase in PC from south to north and from west to east. The sensitivity analysis indicated that PC showed a positive response to variation in the increasing temperature, and the PC of wheat grown in the Huanghuai area was less affected than the PC of wheat grown in other areas. Conversely, solar radiation posed negative effects on the PC in the southwestern area, whereas precipitation had intricate effects on the PC in all areas. Besides, the highest explanation of climate variability during five growth periods contributed 26.0%–47.6% of the PC variability in the northeastern area, whereas the lowest explanation of climate variability during five growth periods only accounted for 2.5%–3.7% of PC variability in the Yangtze River area. Our study further demonstrated that the effects of climate change on wheat grain PC in China were spatially heterogeneous with higher effects on PC in spring wheat-growing areas as compared to winter wheat-growing areas. We suggested that the northern and the northeastern area in China could be developed as alternative areas to produce wheat with high grain PC in the face of climate warming.
... The findings showed that oil concentration was highest at 32/22°C (day/night) and decreased with further increase in temperature. Taub et al. 4 did the meta-analysis for 228 studies to observe the effect of elevated atmospheric CO 2 rate on the protein concentration of major food crops. The results showed that increased CO 2 led to a 1.4% reduction in protein concentration of soybean. ...
... Systems theory may offer new ways to understand how changes in one aspect of the system are likely to affect others, and this concerns both power hierarchies and other ecological factors. For example, the association of dietary protein with appetite is expected to be sensitive to rising CO 2 levels, which have been found to dilute the protein, fiber and micronutrient content of vegetable crops with starches [254,255]. Better understanding of these interrelations, including how the 'competition of agency' interacts with broader ecological factors, will facilitate interventions while avoiding unintended consequences, and may help identify how power dynamics may be targeted in order to achieve the greatest benefits. ...
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The major threat to human societies posed by undernutrition has been recognised for millennia. Despite substantial economic development and scientific innovation, however, progress in addressing this global challenge has been inadequate. Paradoxically, the last half-century also saw the rapid emergence of obesity, first in high-income countries but now also in low- and middle-income countries. Traditionally, these problems were approached separately, but there is increasing recognition that they have common drivers and need integrated responses. The new nutrition reality comprises a global ‘double burden’ of malnutrition, where the challenges of food insecurity, nutritional deficiencies and undernutrition coexist and interact with obesity, sedentary behaviour, unhealthy diets and environments that foster unhealthy behaviour. Beyond immediate efforts to prevent and treat malnutrition, what must change in order to reduce the future burden? Here, we present a conceptual framework that focuses on the deeper structural drivers of malnutrition embedded in society, and their interaction with biological mechanisms of appetite regulation and physiological homeostasis. Building on a review of malnutrition in past societies, our framework brings to the fore the power dynamics that characterise contemporary human food systems at many levels. We focus on the concept of agency, the ability of individuals or organisations to pursue their goals. In globalized food systems, the agency of individuals is directly confronted by the agency of several other types of actor, including corporations, governments and supranational institutions. The intakes of energy and nutrients by individuals are powerfully shaped by this ‘competition of agency’, and we therefore argue that the greatest opportunities to reduce malnutrition lie in rebalancing agency across the competing actors. The effect of the COVID-19 pandemic on food systems and individuals illustrates our conceptual framework. Efforts to improve agency must both drive and respond to complementary efforts to promote and maintain equitable societies and planetary health.
... Carbon fertilization due to elevated CO 2 levels is expected to alleviate the negative impact of temperature increase on yield development, with a stronger benefit for C3 than C4 plants (Fuhrer 2003;Pongratz et al. 2012). The effects of elevated CO 2 levels on plant growth are not expected to act ubiquitously positive but depend in their amplitude on the interaction with regional environments (McGrath and Lobell 2013), on the frequency of droughts (Jin et al. 2018), and will likely decrease the nutritional value of both crops (Taub et al. 2008) and vegetables . A large-scale comparison of yield increases under elevated CO 2 concentrations found 50% lower yield increase for C3 plants grown in the field than indoor and no increase for C4 plants (Long 2006). ...
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Rising temperatures and changing precipitation patterns will affect agricultural production substantially, exposing crops to extended and more intense periods of stress. Therefore, breeding of varieties adapted to the constantly changing conditions is pivotal to enable a quantitatively and qualitatively adequate crop production despite the negative effects of climate change. As it is not yet possible to select for adaptation to future climate scenarios in the field, simulations of future conditions in controlled-environment (CE) phenotyping facilities contribute to the understanding of the plant response to special stress conditions and help breeders to select ideal genotypes which cope with future conditions. CE phenotyping facilities enable the collection of traits that are not easy to measure under field conditions and the assessment of a plant‘s phenotype under repeatable, clearly defined environmental conditions using automated, non-invasive, high-throughput methods. However, extrapolation and translation of results obtained under controlled environments to field environments is ambiguous. This review outlines the opportunities and challenges of phenotyping approaches under controlled environments complementary to conventional field trials. It gives an overview on general principles and introduces existing phenotyping facilities that take up the challenge of obtaining reliable and robust phenotypic data on climate response traits to support breeding of climate-adapted crops.
... The CO 2 concentrations also show a strong positive significant effect, which is consistent with other studies in the literature [22,55]. However, there is also evidence of a possible effect of decreased protein concentration in cereal crops [56,57]. ...
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Agriculture is one of the economic sectors primarily affected by climate change. This impact is very uneven, especially for countries with large territories. This paper examines the contribution of climate change to the improvement in agricultural productivity in Russia over the past two decades. Several ensembles of fixed effects regressions on yields and gross harvests of grain, fruits, and berries, potato, and vegetables were evaluated for a sample of 77 Russian regions over the 2002–2019 period. In contrast to similar studies of the climate impact on Russian agriculture, we considered a larger set of variables, including both Russian and global climate trends, technological factors, and producer prices. Russian weather trends such as winter softening and increase in summer heat have a significant but opposite effect on yields. An interesting finding is a significant and mostly positive influence of global climatic variables, such as the CO2 concentration, El Niño and La Niña events on both harvests and yields. Although technological factors are the main drivers of growth in Russian agricultural performance over the past 20 years, we found a strong positive effect on yield and gross harvest only for mineral fertilizers. The influence of the other variables is mixed, which is mainly due to data quality and aggregation errors.
... A meta-analysis (228 studies) summarized the impact of elevated CO 2 concentration on protein concentration and composition in major food crops (Taub et al. 2008). Protein concentration decreased 10-15% in wheat, rice, and barley; 14% in potatoes; and only 1.4% in soybean. ...
Article
Our global population is growing at a pace to exceed 10 billion people by the year 2050. This growth will place pressure on the agricultural production of food to feed the hungry masses. One category that will be strained is protein. Per capita protein consumption is rising in virtually every country for both nutritional reasons and consumption enjoyment. The United Nations estimates protein demand will double by 2050, and this will result in a critical overall protein shortage if drastic changes are not made in the years preceding these changes. Therefore, the world is in the midst of identifying technological breakthroughs to make protein more readily available and sustainable for future generations. One protein sourcing category that has grown in the past decade is plant-based proteins, which seem to fit criteria established by discerning consumers, including healthy, sustainable, ethical, and relatively inexpensive. Although demand for plant-based protein continues to increase, these proteins are challenging to utilize in novel food formulations. Expected final online publication date for the Annual Review of Food Science and Technology, Volume 13 is March 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
... Higher CO 2 concentrations can speed up the growth of some crops, causing a decrease in nutrient quality of staple plants such as potatoes, barley, rice, and wheat [67][68][69]. Many staple crops had higher carbohydrate concentrations and lower plant-based protein and mineral content in laboratory studies of the impact of CO 2 on human nutrition [29]. ...
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This study investigates the relationship between climate variables such as rainfall amount, temperature, and carbon dioxide (CO2) emission and the triple dimension of food security (availability, accessibility, and utilization) in a panel of 25 sub-Saharan African countries from 1985 to 2018. After testing for cross-sectional dependence, unit root and cointegration, the study estimated the pool mean group (PMG) panel autoregressive distributed lag (ARDL). The empirical outcome revealed that rainfall had a significantly positive effect on food availability, accessibility, and utilization in the long run. In contrast, temperature was harmful to food availability and accessibility and had no impact on food utilization. Lastly, CO2 emission positively impacted food availability and accessibility but did not affect food utilization. The study took a step further by integrating some additional variables and performed the panel fully modified ordinary least squares (FMOLS) and dynamic ordinary least squares (DOLS) regression to ensure the robustness of the preceding PMG results. The control variables yielded meaningful results in most cases, so did the FMOLS and DOLS regression. The Granger causality test was conducted to determine the causal link, if any, among the variables. There was evidence of a short-run causal relationship between food availability and CO2 emission. Food accessibility exhibited a causal association with temperature, whereas food utilization was strongly connected with temperature. CO2 emission was linked to rainfall. Lastly, a bidirectional causal link was found between rainfall and temperature. Recommendations to the national, sub-regional, and regional policymakers are addressed and discussed.
... The rising trend of atmospheric [CO 2 ] is a global sustainability concern for terrestrial and oceanic ecosystems (Lougheed et al. 2020;Wang et al. 2021). The potential impacts of elevated [CO 2 ] (e[CO 2 ]) on crops have been studied in different agro-regions, and meta-analysis reports explicate that the effects are variable with crop species and environments (Taub et al. 2008;Wang et al. 2012;McLachlan et al. 2020). An e[CO 2 ] condition can alter/affect plant physiological functions and yield at variable scales depending on crop species (Wang et al. 2012;Jena et al. 2018), soil type (De Graaff et al. 2006), climate (Feng et al. 2008), and management practices (Hazra et al. 2019). ...
Article
The increasing atmospheric [CO 2 ] would alter soil-plant nutrient dynamics depending on crop species, soil type, and climate. Insights on the impacts of the predicted level of elevated [CO 2 ] (e[CO 2 ]) on the soil-plant-environment system are, therefore, important for strategic nutrient management for future environments. The impacts of e[CO 2 ] environment on soil phosphorus (P) bioavailability and soil-plant P dynamics in chickpea are uncertain in tropical alkaline Vertisols. An open-top chamber-based experiment with e[CO 2 ] (570 ± 30 ppmv) and ambient [CO 2 ] treatments aimed to investigate the impacts of e[CO 2 ] on soil-plant P dynamics, physiology, and yield of chickpea in a moderately alkaline Vertisol of subtropical central India. Experimental findings revealed that the e[CO 2 ] treatment increased Olsen P at flowering stage (+ 13%, p < 0.05), water-soluble carbon (11-14%), and KMnO 4-C (5-14%) at both branching and flowering stages (p < 0.05). Results demonstrated that the increased mobilization of dissolved non-reactive P (NaHCO 3-Po, NaOH-Po) (from branching to flowering) and competitive sorption with higher soluble carbon possibly contributed to the higher available P (Olsen P) under the e[CO 2 ] environment. The e[CO 2 ] treatment had a significant impact on photosynthetic rate (+ 5.3%), stomatal conductance (− 16.5%), and leaf chlorophyll content (+ 5.1%) over the ambient (p < 0.05) but did not alter leaf nitrate reductase activity. The e[CO 2 ] treatment increased plant biomass (+ 25%) and productivity (+ 11.6%), P uptake (+ 16.6%), and physiological P use efficiency (+ 7.1%) (p < 0.05). Thus, it can be concluded that e[CO 2 ] (~ 570 ppmv) could enhance P availability in alkaline Vertisols of subtropical regions favoring P nutrition, physiological activity, and yield of chickpea.
... A significant reduction has been projected for global wheat production of 6.0 ± 2.9% for each degree Celsius increase in global mean temperature, and it should be noted that crop production is also negatively affected by the increase in climate extremes, including changes in rainfall extremes, increases in hot nights (Welch et al. 2010;Okada et al. 2011;García et al. 2018), extremely high daytime temperatures, and water stress. In addition to the consequences for yield, the faster growth rates induced by elevated CO 2 have been found to coincide with lower protein content in several important C3 cereal grains (Myers et al. 2014), consistent with the reduced grain protein content and hence nutritional quality observed by Taub et al. (2008) and Pleijel and Uddling (2012). ...
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Global climate change is shifting temperature and precipitation regimes, which is modifying the environments that define wheat yield and quality. The current work characterises the changes that have occurred in the thermal and hydric environment in two contrasting sites of the wheat-growing region of Argentina, allowing comparison between sites for these changes and for how the changes are accelerating. Temperature and precipitation variables were analysed by regression and trend testing (Mann Kendall), and future projections were made based upon significant relationships. The two sites compared were in the zones around the cities of Azul in the Province of Buenos Aires and Marcos Juárez in the Province of Córdoba, located approximately 500 km apart. The climate data analysed covered the period 1931–2014 for Azul and 1952–2014 for Marcos Juárez. At both sites, temperatures increased significantly in mean and extreme values over these periods, where the rate of change accelerated during the first years of the twenty-first century. The changes observed were in general more pronounced in Marcos Juárez than in Azul. Furthermore, in Marcos Juárez, mean precipitation increased from September to December and there was a higher frequency of extremes of precipitation greater than 100 mm in September and October during the early twenty-first century. Evidence was found for temperature rise and the occurrence of extreme temperature and precipitation events occurring differently between sites, as well as for its acceleration rate in the early twenty-first century. The projected future changes made implied that wheat yield is expected to suffer losses over the coming century.
... With an increase in CO 2 concentration, the chemical composition of crops will shift, resulting in a reduction in most elements, including nitrogen (Loladze, 2002). Doubling of CO 2 concentration can reduce barley grain protein concentration between 10 % and 15 % (Tabu et al., 2008). An excessive nitrogen application cannot fully compensate for such a reduction in protein concertation in cereals (Kimball et al., 2001). ...
Article
Most of the experimental and modeling studies that evaluate the impacts of climate change and variability on barley have been focused on grain yield. However, little is known on the effects of combined change in temperature, CO2 concentration, and extreme events on barley grain quality and how capable are the current process-based crop models capture the signal of climate change on quality traits. Here in this review, we initially explored the response of quality traits of barley to heat, drought, and CO2 concentration from experiential studies. Next, we reviewed the state of the art of some of the current modeling approaches to capture grain quality. Lastly, we suggested possible opportunities to improve current models for tracking the detailed quality traits of barley. Heat and drought stress increase the protein concentration which has a negative effect on malting quality. The rise of CO2 concentration significantly reduces the grain protein, again resulting in a decline of the malting and brewing quality since the nitrogen concentration of grains needs to be kept at a specific level. The current crop models that simulate barley grain quality are limited to simulation of grain nitrogen concentration, size, and number in response to climate extremes and CO2. Nevertheless, crop models fail to account for the complex interactions between the conflicting effects of rising temperatures and droughts as well as increasing CO2 concentrations on grain protein. They have mainly adapted wheat models that cannot capture barley’s protein composition and whole grain malting quality. Implementation of experiments from gene to canopy scales which are explicitly designed to detect the interactions among environmental variables on detailed quality traits and couple the remote sensing plus data-driven approaches to crop models are possible opportunities to improve modeling of barley grain quality. The development of modeling routines can capture the detailed grain quality provide valuable tools for forming climate adaptive strategies. Equally important, they can guide breeding programs to develop climate-resilient but high-quality barley genotypes.
... These factors not only disturb the efficiency of plant systems but also alter the global distribution of plants. The nutrient status of plants is also deteriorating at a faster pace, for instance, the elevated levels of greenhouse gases force a decline in the nitrogen content of non-legume plants (Jablonski et al. 2002;Taub et al. 2008). The increasing global temperature is also affecting oceans as they act as sink for most of the supplementary heat engendered by human-induced climatic changes. ...
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The increased human interventions have forced the global climatic conditions to change at a very faster pace and in a way that seems to be totally uncontrollable and highly impulsive. The elevated levels of carbon dioxide, continuously increasing temperature, altered precipitation patterns, altered moisture content of soils, and greater frequency of some extreme events are affecting every form of life in a significant way. These are affecting the plants systems by altering their geographical distribution, fitness, and productivity. Microbial systems, being the key drivers behind major ecological processes and nutrient cycles, are also being distressed by the continuously changing climatic conditions. The temperature sponsored alteration in global carbon cycling is expected to change the status of soil from “carbon sink” to “carbon source.” The increased rate of microbial respiration and enzymatic activities also bring about quicker mineralization of soil organic matter that is leading toward a reduction in the organic carbon as well as nitrogen content of soil. The microbiological inhabitants are also declining in the uppermost layer of soil owing to the increased surface temperature. The climatic extremes are also known to negatively affect the plant-microbe symbiotic associations that further ensues in a reduced plant fitness. Reduction in the rhizospheric microbial count is leading to a decline in the microbial sequestration of carbon that further accounts for the reduced carbon inputs to the soil systems. As a whole, the altered environmental conditions are altering the microbial as well as plant habitats. The present chapter, therefore, highlights the impacts of changing climatic conditions in special context to soil microorganisms involved in different processes regulating nutrient transformation.
... En cambio, los aumentos en la concentración de CO2 tienen un efecto fertilizador en las plantas, ya que, al haber una mayor disponibilidad de carbono en la atmósfera, aumentan las tasas de asimilación, lo que incrementa las tasas de crecimiento, los rendimientos, y disminuyen las afectaciones derivadas del aumento en la temperatura (Bisbis et al., 2017). Sin embargo, el crecimiento acelerado de las plantas puede tener consecuencias negativas en la producción de los micro y macronutrientes, reduciendo su calidad nutricional (Taub, Miller & Allen., 2008;Bisbis et al., 2017). Aunado a esto se ha sugerido que a mayores concentraciones de CO2 aumenta la susceptibilidad de las plantas a las plagas (Zavala, Casteel, DeLucia & Berenbaum, 2008). ...
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This chapter approaches the relationships between mobility, hydrometeorological phenomena and health and makes a first exercise to try to understand how social inequalities intersect with natural phenomena due to global change, and impact the everyday lives of men and women in urban areas. It is argued that these intersections allow us to understand the socio environmental complexity in cities, as well as those social care practices that express a set of gender norms that prevent the exercise of women rights and allow the reproduction of power relations that maintain social and gender inequality gaps. The chapter proposes a methodological strategy that can allow us to understand how inequality processes, care and environmental degradation are interweave and articulated. Finally, it demonstrates the appropriateness of working together the concepts of habitability and care, in order to orient the climate agenda towards a framework that allow us to achieve socioenvironmental justice under a gender perspective.
... En cambio, los aumentos en la concentración de CO2 tienen un efecto fertilizador en las plantas, ya que, al haber una mayor disponibilidad de carbono en la atmósfera, aumentan las tasas de asimilación, lo que incrementa las tasas de crecimiento, los rendimientos, y disminuyen las afectaciones derivadas del aumento en la temperatura (Bisbis et al., 2017). Sin embargo, el crecimiento acelerado de las plantas puede tener consecuencias negativas en la producción de los micro y macronutrientes, reduciendo su calidad nutricional (Taub, Miller & Allen., 2008;Bisbis et al., 2017). Aunado a esto se ha sugerido que a mayores concentraciones de CO2 aumenta la susceptibilidad de las plantas a las plagas (Zavala, Casteel, DeLucia & Berenbaum, 2008). ...
Chapter
Habitability has diverse meanings depending on the theoretical-conceptual framework and scale used. Here the term “regional habitability” is minted and its relation to a local watershed and global climate change are described. Furthermore, regional habitability is characterized for the Tijuana River Watershed using socio-economic and environmental indicators as well as Material and Energy Flow Analysis to describe the impacts related to the rapid urbanization in such watershed. Results indicated that this process demanded inputs of construction materials and electricity in two or three orders of magnitude; and make Tijuana depend on 90 % of water transferences from the Colorado River with a large energy investment and emission’s generation. The accelerated urbanization is associated to the regional development model as shown through a comparison with Monterrey. It is concluded that this development has not contributed to the urban environmental sustainability but to an environmental emergency; it has not increased urban resilience neither has improved its regional habitability.
Article
Recent advances are revealing mechanisms mediating CO2-regulated stomatal movements in Arabidopsis, stomatal architecture and stomatal movements in grasses, and the long-term impact of CO2 on growth.
Article
The effect of climate change on crop yield in smallholder farms was simulated using the FAO's crop water productivity model AquaCrop and climate change projections from various climate models. This was performed for emission scenarios RCP 4.5 and 8.5 and for time horizons 2030 and 2050. Although the variation in inter-annual rainfall is projected to be substantial, the median projected change in total rainfall is predominantly slightly positive in future years. The climatic changes considered involve temperature increases of between 1.0 °C (2030) and 2.5 °C (2050), and an increase in evapotranspiration of between 3% (2030) and 7% (2050). An in-depth analysis was carried out in four pilot countries: The Gambia, Côte d'Ivoire, Mali and Niger. Four crops and two cultivation methods were considered: irrigated tomato, rainfed sorghum, and rice and maize cultivated both under irrigated and rainfed agriculture. Projections show that if management practices are not improved, climate change will have a negative impact on agricultural production. On average, yield is expected to decline by 5 to 20%, depending on the crop, agro-ecological zone and time horizon. Simulations indicate that the cultivation of sorghum in the Sahelian zone may no longer be feasible under future climatic conditions. If management practices are not improved, the yield gap increases with climate change. To benefit from CO2 fertilization in future years, future soil fertility needs to increase by at least 15 to 20% in order to maintain current levels. Improved fertility management could lead to an increase in crop yields of between 5 and 14% for irrigated tomato and irrigated and rainfed rice. The impact of future climate changes on maize yield, maize being a C4 crop which benefits less from CO2 fertilization, was mostly negative even with improved soil fertility management.
Article
The extent to which rising atmospheric CO2 concentration has already influenced food production and quality is uncertain. Here, we analyzed annual field trials of fall-planted common wheat in California from 1985 to 2019, a period during which global atmospheric CO2 concentration increased 19%. Even after accounting for other major factors (cultivar, location, degree-days, soil temperature, total water applied, nitrogen fertilization, and pathogen infestation), wheat grain yield and protein yield declined 13% over this period, but grain protein content did not change. These results suggest that exposure to gradual CO2 enrichment over the past 35 years has adversely affected wheat grain and protein yield, but not grain protein content.
Chapter
The concentration of atmospheric carbon dioxide (CO2) has almost doubled since the preindustrial era due to global climate change and is expected to further increase if the current emission rates are not controlled. The impacts of elevated CO2 (e[CO2]) on growth, development, and yield of plant species, particularly crops, are very important concerns for the scientist. This is due to dynamic implications on global agricultural production and food security in the climate change scenario. Crops respond to the e[CO2] by stimulating the photosynthetic rate. which boosts crop yield. Higher levels of atmospheric carbon act like a carbon fertilizer for the plants and results in an increase in plant growth and productivity. Cereal crops grow larger in size and exhibit faster growth rates under e[CO2], and biomass production becomes higher. Crops have evolved strategies to enhance their physiological performance by increasing water use efficiency and reducing the transpirational water loss as well as lowering stomatal conductance under e[CO2]. C3 plants exhibit considerably higher increases in yield due to e[CO2] ranging from 20% and 35% as compared to C4 crops with only 10% to 15%. e[CO2] influences the qualitative attributes of crops, including the concentration of nutrients, which are fundamental food quality attributes having diverse implications on agricultural production, market value of crops as well as impacts on human health. Sharp declines are projected in the protein content and free amino acid of cereals under e[CO2] conditions. Under realistic field conditions experiments, free-air CO2 enrichment technology revealed significant increases in the photosynthesis activity, leaf carbohydrates, starch and sugars whereas the concentration of nitrogen per unit leaf mass has been found to decrease. The relative yield responses of grain crops under e[CO2] might increase under limiting nutrient and water conditions due to physiological adaptations. The major C3 cereals, including wheat and rice, undergo major shifts in physiological responses and C:N metabolism in response to e[CO2], However, a reduction in nutritional quality under e[CO2] appears to be a major challenge.
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Key message Heat stress (HS) under well-watered conditions was not detrimental to leaf photosynthesis or yield but modified the elevated CO2 response of photosynthesis and yield in two contrasting wheat cultivars. Abstract Climate change is increasing the frequency of extreme events such as heat waves, adversely affecting crop productivity. While positive impacts of elevated carbon dioxide (eCO2) on crop productivity are evident, the interactive effects of eCO2 and environmental stresses are still unclear. To investigate the interactive effects of elevated CO2 and heat stress (HS), we grew two contrasting wheat cultivars, early-maturing Scout and high-tillering Yitpi, under non-limiting water and nutrients at ambient (aCO2, 450 ppm) or elevated (eCO2, 650 ppm) CO2 and 22 °C in the glasshouse. Plants were exposed to two 3-day HS cycles at the vegetative (38.1 °C) and/or flowering (33.5 °C) stage. At aCO2, both wheat cultivars showed similar responses of photosynthesis and mesophyll conductance to temperature and produced similar grain yield. Relative to aCO2, eCO2 enhanced photosynthesis rate and reduced stomatal conductance and maximal carboxylation rate (Vcmax). During HS, high temperature stimulated photosynthesis at eCO2 in both cultivars, while eCO2 stimulated photosynthesis in Scout. Electron transport rate (Jmax) was unaffected by any treatment. eCO2 equally enhanced biomass and grain yield of both cultivars in control, but not HS, plants. HS reduced biomass and yield of Scout at eCO2. Yitpi, the cultivar with higher grain nitrogen, underwent a trade-off between grain yield and nitrogen. In conclusion, eCO2 improved photosynthesis of control and HS wheat, and improved biomass and grain yield of control plants only. Under well-watered conditions, HS was not detrimental to photosynthesis or growth but precluded a yield response to eCO2.
Chapter
Climate change is one of the alarming environmental concerns in the twenty-first century and so on affecting diverse ecosystems at various scales. Diversified plant species provides food, energy, health and other ecosystem services to human livelihood. Severely affected plant diversity due to climate change is a matter of great concern among scientists, policy makers and rising population. Hence, assessment of climate change-associated threats and opportunities to plant diversity become utterly important. Climate change has notable impact on growth, development as well as the reproductive success of plants, majorly due to change in the micro- or macro climate conditions. It also depends on the plant life form or plant groups as per-intrinsic tolerance and adaptation capacity of diverse group of plants. Multiple stresses co-occurring together under climate change vary greatly within plant group or plant types. In this chapter, we highlighted the threat posed by climate change to the plant diversity as a whole categorised under group, namely, algae, bryophyta and pteridophyte extended to gymnosperms and to the advanced or higher groups of plants such as angiosperms. In the ms the adaptive response of plant species distributed among the above group’s opportunities available to ensure ecosystems structure, processes and services were also explored and documented.
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Climate change is already a reality for livestock production. In contrast to the ruminant species, little is known about the impacts and the vulnerability of pig European Union (EU) sector to climate warming. This review deals with the potential and the already measurable effects of climate change in pig production. Based on evidences published in the literature, climate change may reduce EU pig productivity by indirectly reducing the availability of crops usually used in pig feeding, spreading the vector or pathogen to new locations and increasing the risk of exposure to cereals contaminated with mycotoxins; and directly mainly by inducing heat stress and increasing the animal’s susceptibility to various diseases. Provision of realistic projections of possible impacts of future climate changes on EU pig sector is a prerequisite to evaluate its vulnerability and propose effective adaptation strategies. Simulation modelling approach is the most commonly used approach for exploring the effects of medium or long-term climate change/variability in pig production. One of the main challenges for this modelling approach is to account for both direct and indirect possible effects but also to uncertainties in parameter values that substantially increase the uncertainty estimates for model projections. The last part of the paper focus on the main issues that still need to be overcome for developing a decision support tools for simulating the direct and indirect effect of climate change in pig farms.
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This report defines the relationship between climate change and public health, and offers insights for action.
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Compared with growth and yield, far less attention has been devoted to the impact of elevated CO2 on rice grain quality. Exposure to elevated CO2 induces numerous physiological changes in plants that can alter the chemical composition and thus the quality of rice grains. This meta-analysis was conducted to synthesize the effect of free air CO2 enrichment (FACE, approximately 550 μmol mol⁻¹) on grain quality of rice grown under open field conditions. Factors that could modify the CO2 effects were also investigated. They included cultivars, nitrogen applications, environmental temperatures and grain types. On average, elevated CO2 decreased head rice percentage by 8%, which led to no increase in head rice yield, despite substantial increases of brown rice yield and white rice yield that were obtained under FACE conditions. Elevated [CO2] increased chalky grain percentage by 26% and chalkiness degree by 30%, which significantly impaired rice appearance. However, the cooking and eating quality was improved by elevated [CO2], as indicated by the changes in starch RVA profiles and the palatability of cooked rice. The nutritional value of FACE rice declined as shown by the 2–9% decreases in the concentrations of nitrogen, phosphorus, magnesium, sulfur, zinc, iron, copper, manganese and amino acids; meanwhile the anti-nutrient phytate and the molar ratio of phytate to zinc were increased. High nitrogen application alleviated negative effects of elevated [CO2] on milling quality and rice appearance but further decreased the bioavailability of essential nutrients. The CO2-induced decreases in element concentrations of white rice were generally higher than those in brown rice. In general, CO2-induced changes on grain quality were seldom modified by rice cultivars, temperatures or experimental locations.
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Climate change poses a serious threat to crop productivity. The rise in CO2 levels, air temperature, soil salinity and variability in precipitation are the key factors that contribute to yield loss. Sorghum stands in the arid and semi-arid regions of the world that are particularly vulnerable to climate change. A comprehensive assessment of its vulnerability and resilience is required to adopt appropriate mitigation strategies. Here, we provide an overview of the projected and observed impact of the rise in temperature, CO2, salinity, drought and flooding stress on plant physiology, growth and development, and overall productivity of sorghum. While an increase in CO2 has been projected to enhance sorghum yields, a decrease in precipitation along with temperature rise would negatively impact sorghum productivity. Although sorghum is moderately tolerant to salinity and waterlogging, screening of germplasm for selection of improved varieties and development of tolerant cultivars is necessary for superior performance. The best agricultural practices, technological advances, and genetic enhancement desirable to mitigate the impact of climate change on sorghum productivity have been discussed. © 2022, The Author(s), under exclusive license to Springer Nature Switzerland AG.
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N and S play a significant role in plant growth and development and stimulate the production of secondary metabolites with anti-microbial properties. Under elevated CO2, plants raise their rate of carbon fixation causing increments across the synthesis of carbon that further lead to increased synthesis of carbon-based defence compounds and decrements across the concentrations of N and S in plant tissues. A pot experiment was performed in open-top chambers (OTCs) with ambient CO2 (390 ppm) and elevated CO2 (550 ppm), and mustard plants were supplemented with single doses of N and S separately as well as in combination. Furthermore, to monitor changes in defence ability, mustard plants were challenged with Alternaria brassicae and disease severity was assessed. Significant interactions were evident between CO2 and N and CO2 and S during the vegetative stage but not on the reproductive stage. Additive effects of both the nutrients and CO2 concentration were observed on physiological (net photosynthetic rate, stomatal conductance, sugars, proteins, C:N ratio) as well as defence markers phenylalanine ammonia-lyase enzyme and phenol concentration and disease severity. Combined nutrient treatment with N and S under elevated CO2 led to maximum enhancement of overall plant growth and defence in comparison to individual nutrient treatments. Mustard plants fertilized with N and S alone or in combination under enhanced CO2 improved plant’s growth and defence.
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Carbon dioxide CO2 increasing 2 ppm yearly since developed countries started elimination of NOx and elimination of NP. Global warming is happening by the decrease of CO2 assimilation from insufficient supply of NP fertilyzer. Developed countries hated NOx and NP and are eliminating NOx and NP. Japan is criticized as increasing much CO2. Japan is eliminating NOx,NP completely using much electricity producing 2 billion tone CO2 for the elimination of NOx and NP. Fish production of Japan dropped to 10%. GDP do not increase. If developed countries stop elimination of NOx,NP . CO2 assimilation is activated. Production of grain and fish increase. DGP will increase and global warming will stop.
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The rapid escalation in atmospheric carbon dioxide (CO2) is an important cause of global climate change that determines global crop productivity. Under elevated CO2 (EC), there is an initial increase in the rate of photosynthesis (PN) that is frequently accompanied by a decrease of PN and an overall decline in nitrogen (N) and protein concentration. Increasing CO2 concentrations results in a general decrease in the nutritional quality of plant products and thus impacts the food and dietary requirements of the global population. EC often results in a significant increase in the nonstructural carbohydrates and total sugar content while reducing grain proteins and cooking quality. Crops grown under EC also exhibits an average reduction of 8% in 25 minerals, including calcium, potassium, zinc, and iron. Exposure to EC also decreases the ratio of minerals to carbohydrates leading to irreversible impacts on human health, reduction in immunity, malnutrition and stunted growth in children, rise in maternal and child deaths, and also obesity due to the carbohydrate-rich diet. The mechanistic understanding of reduction in crop and grain quality under EC is limited. The dilution of N metabolites and minerals due to higher carbon accumulation, restriction in nutrient uptake due to lower transpiration rate, and reductant availability are the foremost reasons. Recent evidence also suggests the regulatory role of reactive oxygen and nitrogen species in EC-mediated changes in N metabolism and uptake. The current understanding advocates the prominence of identifying CO2 responsive crop genotypes and using genotype-specific fertilizer management for meeting food and nutritional security needs under future EC scenarios.
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Global warming is caused by retardation of CO2 assimilation by scare of nitrogen and phosphorous Developed countries are tried to purify air and water by NOx and NP elimination at around 1980. Then CO2 assimilation is retarded. CO2 fix is retarded. Agriculture and fish industry are retarded DGP increase rates of these countries are low. On the contrary, developing countries like China, India and Indonesia, they do not eliminate NOx and NP.and use as fertilizer. Then CO2 assimilation is activated CO2 fix is activated. Agriculture and fish industries are activated. DGP increase rates of these countries are high. We must promote CO2 assimilation by complete use of NOx and NP in waste water. And addition of fertilizer to the sea will increase CO2 assimilation and fish production. Promotion of CO2 assimilation by sufficient supply of nitrogen and phosphorous is easiest method to fit Paris agreement and to protect global warming and to increase DGP and national wealth.
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Rising global temperatures are causing major physical, chemical, and ecological changes in the planet. There is wide consensus among scientific organizations and climatologists that these broad effects, known as “climate change,” are the result of contemporary human activity. Climate change poses threats to human health, safety, and security, and children are uniquely vulnerable to these threats. The effects of climate change on child health include: physical and psychological sequelae of weather disasters; increased heat stress; decreased air quality; altered disease patterns of some climate-sensitive infections; and food, water, and nutrient insecurity in vulnerable regions. The social foundations of children’s mental and physical health are threatened by the specter of far-reaching effects of unchecked climate change, including community and global instability, mass migrations, and increased conflict. Given this knowledge, failure to take prompt, substantive action would be an act of injustice to all children. A paradigm shift in production and consumption of energy is both a necessity and an opportunity for major innovation, job creation, and significant, immediate associated health benefits. Pediatricians have a uniquely valuable role to play in the societal response to this global challenge.
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Background Elevated CO2 usually reduces levels of proteins and essential micronutrients in crops. The adoption of early-maturing varieties may minimise the deleterious effect of climate change on farming activities. Since legumes stand out for their high nutritional quality the objective was to study if the atmospheric CO2 concentration affected growth, yield and food quality of early-maturing cultivars of pea, snap bean and faba bean. Plants grew in greenhouses either at ambient (ACO2, 392 μmol mol⁻¹) or under elevated (ECO2, 700 μmol mol⁻¹) CO2. Minerals, proteins, sugars and phenolic compounds were measured in grains of pea and faba bean, and in pods of snap bean. Results The effect of ECO2 depended on legume species, being more evident for food quality than for vegetative growth and yield. ECO2 increased Fe and P in faba bean grains, and Ca in snap bean pods. Under ECO2, grains of pea and faba bean increased, respectively, levels of proteins and phenolics, and the sugars to protein ratio decreased in pods of snap bean. Conclusion Early-maturing varieties of legumes appear as an interesting tool to cope with the negative effects that a long exposure to rising CO2 can exert on food quality. This article is protected by copyright. All rights reserved.
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It is well established that isoflavone contents vary considerably in seeds, roots, leaves, and other plant parts depending on the genotype, environmental factors, growth conditions, and seed developmental stages. In this chapter, we summarized the effects of environmental and growth conditions including temperature, light, rainfall, seed storage, seed size, water availability, growing season, soil conditions, presence or absence of elicitors, nitrogen application, irrigation, row spacing, and other environmental factors on isoflavone contents. Few other studies showed that isoflavones accumulate in soybean seeds due to biotic stresses from pathogen infections from bacteria, fungi, and viruses.
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Like other seed composition traits organic and amino acids, macronutrients, macronutrients, and sugars’ contents vary considerably in soybean seeds depending on the genotype, biotic, and abiotic factors. In this chapter, we first summarized the role of organic and amino acids, macronutrients, macronutrients, sugars, and other compounds in seed development as well as the effects of biotic and abiotic factors on seed development. Finally, we summarized QTL mapping data for amino acids, macronutrients, macronutrients, and sugars’ contents and candidate genes for these seed composition traits for the past two decades (2000–2020). These findings will help breeders and farmers to develop soybean cultivars with high contents of amino acids and desired combinations of sugars and beneficial mineral nutrients.
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Soybean is a major crop in the world and a source of high-quality protein, oil, and other nutrients. Soybean seed protein, oil, fatty acids, and amino acids determine seed nutritional qualities essential for human nutrition and livestock meal. Breeders’ goals for desirable seed nutrients include high oleic and low linolenic acids, low phytic acid, high sucrose, and low raffinose and stachyose levels. Soybeans with higher levels of oleic acid or lower levels of linoleic or linolenic acids are more desirable for human consumption than saturated fatty acids such as palmitic and stearic acids. However, higher levels of oleic acid and low levels of linoleic and linolenic acid are desirable by the industry as they contribute to oil stability, short shelf life, and less rancidity. This trait is desirable because it can minimize hydrogenation of the oil. Hydrogenation has been reported to have undesirable health effects by increasing the risk of coronary heart disease due to higher LDL-cholesterol and lower HDL-cholesterol. This chapter will focus on reviewing soybean seed protein, oil, and fatty acids and highlight the main research conducted on improving soybean seed nutritional qualities from the perspectives of genetic, environmental, and agricultural practices. This chapter will be a useful resource for soybean researchers and growers to advance our understanding of soybean seed quality research to enable producers to effectively compete nationally and internationally in soybean markets.
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Elevated CO2 (eCO2) and high temperatures are known to affect plant nitrogen (N) metabolism. Though the combined effects of eCO2 and chronic warming on plant N relations have been studied in some detail, a comprehensive statistical review on this topic is lacking. This meta-analysis examined the effects of eCO2 plus warming on shoot and root %N, tissue protein concentration (root, shoot, and grain), and N-uptake rate. In the analyses, the eCO2 treatment was categorized into two classes (<300 or ≥300 ppm above ambient or control), the temperature treatment was categorized into three classes (<1.5, 1.5-5, and >5 oC above ambient or control), plant species were categorized based on growth form and functional group, and CO2 treatment technique was also investigated. Elevated CO2 alone or in combination with warming reduced shoot %N (more so at ≥300 vs. <300 ppm above ambient CO2), while root %N was significantly reduced only by eCO2; warming alone often increased shoot %N, but mostly did not affect root %N. Decreased shoot %N with eCO2 alone or eCO2 plus warming was greater for woody and non-woody dicots than for grasses, and for legumes than non-legumes. Though root N-uptake rate was unaffected by eCO2, eCO2 plus warming decreased N-uptake rate, while warming alone increased it. Similar to %N, protein concentration decreased with eCO2 in shoots and grain (but not roots), increased with warming in grain, and decreased with eCO2 and warming in grain. In summary, any benefits of warming to plant N status and root N-uptake rate will generally be offset by negative effects of eCO2. Hence, concomitant increases in CO2 and temperature are likely to negate or decrease the nutritional quality of plant tissue consumed as food by decreasing shoot %N and shoot and/or grain protein concentration, caused, at least in part, by decreased root N-uptake rate.
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Three winter wheat varieties were grown in growth chambers under controlled environmental conditions at two atmospheric CO2 concentrations (375 and 750 μmol*mol-1) with either an ambient temperature regime or with heat stress during grain filling (max 35°C, 8 hours a day for 15 days). Data on the aboveground biomass, tiller and ear number, yield components, harvest index, the protein content of the wholemeal and the functional parameters of the flour were determined after harvest. Mv Martina, a variety with very high yield potential, responded very positively to CO 2 treatment, exhibiting an increase in the tiller and ear number and in the number of grains per plant, resulting in 38 % higher yield without a deterioration in the grain quality. Neither CO2 nor heat stress had a negative effect on the flour quality of this variety as the protein content and SDS sedimentation volumes increased in both treatments. Increased CO 2 had less influence on the yield of the other varieties, where the grain quality either decreased or remained at a similar level after CO 2 enrichment. Heat stress had a negative effect on TKW and grain yield, but this could be counterbalanced by elevated CO2 level in two varieties. Elevated CO2 and high temperature had opposite effects on the protein and gluten contents (except in Mv Martina), but the gluten index was lowest when both factors were present.
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N acquisition often lags behind accelerated C gain in plants exposed to CO2-enriched atmospheres. To help resolve the causes of this lag, we considered its possible link with stomatal closure, a common first-order response to elevated CO2 that can decrease transpiration. Specifically, we tested the hypothesis that declines in transpiration, and hence mass flow of soil solution, can decrease delivery of mobile N to the root and thereby limit plant N acquisition. We altered transpiration by manipulating relative humidity (RH) and atmospheric [CO2]. During a 7-d period, we grew potted cottonwood (Populus deltoides Bartr.) trees in humidified (76% RH) and non-humidified (43% RH) glasshouses ventilated with either CO2-enriched or non-enriched air (~1000 vs ~380 μmol mol–1). We monitored effects of elevated humidity and/or CO2 on stomatal conductance, whole-plant transpiration, plant biomass gain, and N accumulation. To facilitate the latter, NO3– enriched in 15N (5 atom%) was added to all pots at the outset of the experiment. Transpiration and 15N accumulation decreased when either CO2 or humidity were elevated. The disparity between N accumulation and accelerated C gain in elevated CO2 led to a 19% decrease in shoot N concentration relative to ambient CO2. Across all treatments, 15N gain was positively correlated with root mass (P<0.0001), and a significant portion of the remaining variation (44%) was positively related to transpiration per unit root mass. At a given humidity, transpiration per unit leaf area was positively related to stomatal conductance. Thus, declines in plant N concentration and/or content under CO2 enrichment may be attributable in part to associated decreases in stomatal conductance and transpiration.
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The influence of elevated CO 2 (350, 550 or 900 litre litre -1) and N supply ranging from deficient to excess (0-133 mg N kg -1 soil week -1) on leaf N concentration and shoot growth of wheat cv. Hartog, was investigated. Shoot growth was 30% greater at 550 litre litre -1 compared to ambient CO 2 at all levels of N supply. At 900 litre litre -1 CO 2 concentration, no increase in shoot growth was observed at low N supply. However, growth more than doubled at high N supply (67 mg N kg -1). Growth effects were closely matched by changes in sink development. It is suggested that sink strength, mediated through N supply, controlled the shoot growth response to elevated CO 2. Shoot N concentration was lower at each level of CO 2 enrichment and the greatest effect (30% reduction) occurred at 900 litre CO 2 litre -1 and 33 mg N kg -1. The effect of high CO 2 on shoot N concentration diminished as N supply increased and, at the highest N addition rate, only a 7% reduction in shoot N concentration was evident. Changes in foliar N concentration due to CO 2 enrichment were closely correlated with lower soluble protein concentration, accounting for 58% of the total leaf N reduction. Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) levels were also reduced at high CO 2 and N was allocated away from Rubisco and into other soluble proteins at high CO 2 when N supply was low. Non-structural carbohydrate concentration (dry weight basis) was greatest at 900 litre CO 2 litre -1 and low N supply and may have reduced Rubisco concentration via a feed-back response. Critical foliar N concentrations (N concentrations at 90% of maximum shoot growth) were reduced from 43 mg g -1 at ambient CO 2, to 39 and 38 mg g -1 at 550 and 900 litre CO 2 litre -1, respectively. Elevated CO 2 and N supplies of 0-17 mg N kg -1 reduced flour protein concentration by 9-13%.
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Wheat ( Triticum aestivum) cv. Hartog and Rosella were grown at CO 2 concentrations of 280 l litre -1 (representing the pre-industrial CO 2 concentration), 350 l litre -1 (ambient) or 900 l litre -1 (an extreme projection of atmospheric CO 2 concentration). The plants were grown in naturally lit glasshouses in 7 litre pots containing soil to which basal nutrients had been added and the pH adjusted to 6.5. Hartog yielded 2.4 g of grain per plant when grown at 280 l CO 2 litre -1. This yield was increased by 38% and 75% at CO 2 concentrations of 350 and 900 l litre -1, respectively. These changes were due to increase in both grain number and individual grain weight as the level of CO 2 was raised. The yield of Rosella was unaffected by altering the CO 2 concentration. Increasing the CO 2 concentration reduced grain protein concentration of cv. Hartog from 17.4% at 280 l CO 2 litre -1 to 16.5% and 16% at CO 2 concentrations of 350 and 900 l litre -1, respectively. The grain protein concentration of cv. Rosella was reduced from 10.7% to 10.2% by increasing the CO 2 concentration from 280 l litre -1 to 350 l litre -1; however, an additional increase in the CO 2 concentration to 900 l litre -1 had no effect on grain protein concentration. In Hartog flour, the highest proportion of polymeric protein in the flour (7.7%) occurred at 280 l CO 2 litre -1. This was reduced to 6.3% at 350 l CO 2 litre -1 but then increased again to 7.0% at 900 l CO 2 litre -1. These changes in concentration of polymeric protein were correlated ( r=0.58) with changes in mixing properties. The mixing time required to produce optimum dough strength was greatest at 900 l CO 2 litre -1 (181 s), then 141 s and 151 s at 350 and 280 l CO 2 litre -1, respectively. These changes in mixing time could not be explained by changes in grain protein concentration. The proportion of 'B' starch granules (<10 m diameter) increased from 25% of total weight of starch at 280 l CO 2 litre -1 to 30% at CO 2 concentrations 350 and 900 l litre -1. There were generally no effects of CO 2 concentration on dough mixing properties or starch granule size distribution for Rosella.
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Meta-analysis is a statistical technique that allows one to combine the results from multiple studies to glean inferences on the overall importance of various phenomena. This method can prove to be more informative than common ''vote counting,'' in which the number of significant results is compared to the number with nonsignificant results to determine whether the phenomenon of interest is globally important. While the use of meta- analysis is widespread in medicine and the social sciences, only recently has it been applied to ecological questions. We compared the results of parametric confidence limits and ho- mogeneity statistics commonly obtained through meta-analysis to those obtained from re- sampling methods to ascertain the robustness of standard meta-analytic techniques. We found that confidence limits based on bootstrapping methods were wider than standard confidence limits, implying that resampling estimates are more conservative. In addition, we found that significance tests based on homogeneity statistics differed occasionally from results of randomization tests, implying that inferences based solely on chi-square signif- icance tests may lead to erroneous conclusions. We conclude that resampling methods should be incorporated in meta-analysis studies, to ensure proper evaluation of main effects in ecological studies.
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An analysis was undertaken of the growth of soybeans grown in pots in open top field chambers at six COâ concentrations ranging from 332 ..mu..L L⁻¹ (ambient) to 910 ..mu..L L⁻¹. Major growth response occurred with the first increments of added COâ with a maximum 66% increase in total vegetative dry matter at the 910 ..mu..L L⁻¹ COâ level. Dry weight increases were proportionate among vegetative plant parts, although the harvest index was found to decrease slightly. Greater absolute growth rates in elevated COâ treatments were associated with greater rates of branch and internode elongation, leaf initiation, and leaf expansion. Yield increases represented greater seed numbers per plant rather than larger seeds. Percentage protein of seed decreased with COâ enrichment. In the interval from day 5 to 2 weeks after planting, mean relative growth rate (RGR) increased asymptotically with COâ concentration. Of the two components of RGR, the mean net assimilation rate (NAR) increased dramatically and mean leaf area ratio (LAR) decreased. In the intervals from week 2 to 7 and from week 7 to 12, RGR became constant across COâ treatments as the positive response of NAR and the negative response of LAR became less pronounced. Both RGR and NAR fell through the vegetative growth phase at each COâ level. The adjustment in LAR resulted from a decrease in specific leaf area while leaf weight ratio remained unaffected by COâ.
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Abstract The effects of elevated [CO2] on 25 variables describing soybean physiology, growth and yield are reviewed using meta-analytic techniques. This is the first meta-analysis to our knowledge performed on a single crop species and summarizes the effects of 111 studies. These primary studies include numerous soybean growth forms, various stress and experimental treatments, and a range of elevated [CO2] levels (from 450 to 1250 p.p.m.), with a mean of 689 p.p.m. across all studies. Stimulation of soybean leaf CO2 assimilation rate with growth at elevated [CO2] was 39%, despite a 40% decrease in stomatal conductance and a 11% decrease in Rubisco activity. Increased leaf CO2 uptake combined with an 18% stimulation in leaf area to provide a 59% increase in canopy photosynthetic rate. The increase in total dry weight was lower at 37%, and seed yield still lower at 24%. This shows that even in an agronomic species selected for maximum investment in seed, several plant level feedbacks prevent additional investment in reproduction, such that yield fails to reflect fully the increase in whole plant carbon uptake. Large soil containers (> 9 L) have been considered adequate for assessing plant responses to elevated [CO2]. However, in open-top chamber experiments, soybeans grown in large pots showed a significant threefold smaller stimulation in yield than soybeans grown in the ground. This suggests that conclusions about plant yield based on pot studies, even when using very large containers, are a poor reflection of performance in the absence of any physical restriction on root growth. This review supports a number of current paradigms of plant responses to elevated [CO2]. Namely, stimulation of photosynthesis is greater in plants that fix N and have additional carbohydrate sinks in nodules. This supports the notion that photosynthetic capacity decreases when plants are N-limited, but not when plants have adequate N and sink strength. The root : shoot ratio did not change with growth at elevated [CO2], sustaining the charge that biomass allocation is unaffected by growth at elevated [CO2] when plant size and ontogeny are considered.
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It has become of interest to study long-term effects of COâ concentration on plant growth, because intensive burning of fossil fuels and destruction of forests promise to continue the recent rise in atmospheric partial pressures of COâ into the next century (Bolin, 1977; Stuiver, 1978). Effects of COâ enrichment on growth of crop and forest species were therefore studied for the first time in the field in open top exposure chambers at daytime mean COâ concentrations of 612, 936, 1292, and 1638 mg m⁻³, and in ambient control plots. Increased growth of plant parts of corn (Zea mays L. 'Golden Bantam'), soybean (Glycine max L. (Merr.) 'Ransom'), loblolly pine (Pinus taeda L.), and sweetgum (Liquidambar styraciflua L.) were recorded. Growth increases for soybean and sweetgum in elevated COâ atmospheres were due to increases in leaf area and photosynthesis per unit leaf area, and decreases in conductance and, therefore, water use. For corn, however, photosynthesis was unaffected by COâ enhancement, and growth stimulation appeared to be due to lowered conductance and increased water use efficiency alone.
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Interactions involving carbon (C) and nitrogen (N) likely modu- late terrestrial ecosystem responses to elevated atmospheric carbon dioxide (CO2) levels at scales from the leaf to the globe and from the second to the century. In particular, response to elevated CO2 may generally be smaller at low relative to high soil N supply and, in turn, elevated CO2 may influence soil N processes that regulate N availability to plants. Such responses could constrain the capacity of terrestrial ecosystems to acquire and store C under rising ele- vated CO2 levels. This review highlights the theory and empirical evidence behind these potential interactions. We address effects on photosynthesis, primary production, biogeochemistry, trophic in- teractions, and interactions with other resources and environmental factors, focusing as much as possible on evidence from long-term field experiments.
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Increasing atmospheric CO2 concentrations [CO2] have the potential to enhance growth and yield of agricultural plants. Con-comitantly plants grown under high [CO2] show significant changes of the chemical composition of their foliage and of other plant parts. Particularly, high [CO2] result in a decrease of plant nitrogen (N) concentration, which may have serious consequences for crop quality. This presentation summarizes the results of a variety of CO2 enrichment studies with pasture plants (Lolium spp., Trifolium repens) and cereal species (Triticum aestivum, Hordeum vulgare) which were conducted at our laboratory under different growth and CO2 exposure conditions ranging from controlled environment studies to investigations under free air carbon dioxide enrichment (FACE). With the exception of clover in all experiments a CO2-induced decline of forage and grain N concentration was observed. The magnitude of this reduction differed between species, cultivars, management conditions (N fertilization) and CO2 exposure conditions. No unambiguous evidence was obtained whether N fertilization can contribute to meet the quality requirements for cereals and grass monocultures with respect to tissue N concentrations in a future high-CO2 world. As shown in the FACE experiments current application rates of N fertilizers are inadequate to achieve quality standards.
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Two varieties of spring wheat were cultured in temperature gradient tunnels with two CO2 concentrations and two different temperatures. We discuss the effects of these three variables on the mineral chemical composition of the plant samples, separated into fractions. taken during two phases: a few days before anthesis and at harvesting. The variety of the plant and the CO2 concentration were the variables found to exert the greatest influence, the glumes and rachis, the straw and the rest of the stem (without the last internode) being the parts of the plant that most frequently showed different values owing to the effect of thr variables. The nutrients N and Mg were the most sensitive to differentiation in the plants owing to the action of the variables. Iron was seen to be less sensitive. as was P.
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The effects of elevated carbon dioxide on plant–herbivore interactions have been summarized in a number of narrative reviews and metaanalyses, while accompanying elevation of temperature has not received sufficient attention. The goal of our study is to search, by means of metaanalysis, for a general pattern in responses of herbivores, and plant characteristics important for herbivores, to simultaneous experimental increase of carbon dioxide and temperature (ECET) in comparison with both ambient conditions and responses to elevated CO2 (EC) and temperature (ET) applied separately. Our database includes 42 papers describing studies of 31 plant species and seven herbivore species. Nitrogen concentration and C/N ratio in plants decreased under both EC and ECET treatments, whereas ET had no significant effect. Concentrations of nonstructural carbohydrates and phenolics increased in EC, decreased in ET and did not change in ECET treatments, whereas terpenes did not respond to EC but increased in both ET and ECET; leaf toughness increased in both EC and ECET. Responses of defensive secondary compounds to treatments differed between woody and green tissues as well as between gymnosperm and angiosperm plants. Insect herbivore performance was adversely affected by EC, favoured by ET, and not modified by ECET. Our analysis allowed to distinguish three types of relationships between CO2 and temperature elevation: (1) responses to EC do not depend on temperature (nitrogen, C/N, leaf toughness, phenolics in angiosperm leaves), (2) responses to EC are mitigated by ET (sugars and starch, terpenes in needles of gymnosperms, insect performance) and (3) effects emerge only under ECET (nitrogen in gymnosperms, and phenolics and terpenes in woody tissues). This result indicates that conclusions of CO2 elevation studies cannot be directly extrapolated to a more realistic climate change scenario. The predicted negative effects of CO2 elevation on herbivores are likely to be mitigated by temperature increase.
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This review first summarizes the numerous studies that have described the interaction between the nitrogen supply and the response of photosynthesis, metabolism and growth to elevated [CO2]. The initial stimulation of photosynthesis in elevated [CO2] is often followed by a decline of photosynthesis, that is typically accompanied by a decrease of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), an accumulation of carbohydrate especially starch, and a decrease of the nitrogen concentration in the plant. These changes are particularly marked when the nitrogen supply is low, whereas when the nitrogen supply is adequate there is no acclimation of photosynthesis, no major decrease in the internal concentration of nitrogen or the levels of nitrogen metabolites, and growth is stimulated markedly. Second, emerging evidence is discussed that signals derived from nitrate and nitrogen metabolites such as glutamine act to regulate the expression of genes involved in nitrate and ammonium uptake and assimilation, organic acid synthesis and starch accumulation, to modulate the sugar-mediated repression of the expression of genes involved in photosynthesis, and to modulate whole plant events including shoot–root allocation, root architecture and flowering. Third, increased rates of growth in elevated [CO2] will require higher rates of inorganic nitrogen uptake and assimilation. Recent evidence is discussed that an increased supply of sugars can increase the rates of nitrate and ammonium uptake and assimilation, the synthesis of organic acid acceptors, and the synthesis of amino acids. Fourth, interpretation of experiments in elevated [CO2] requires that the nitrogen status of the plants is monitored. The suitability of different criteria to assess the plant nitrogen status is critically discussed. Finally the review returns to experiments with elevated [CO2] and discusses the following topics: is, and if so how, are nitrate and ammonium uptake and metabolism stimulated in elevated [CO2], and does the result depend on the nitrogen supply? Is acclimation of photosynthesis the result of sugar-mediated repression of gene expression, end-product feedback of photosynthesis, nitrogen-induced senescence, or ontogenetic drift? Is the accumulation of starch a passive response to increased carbohydrate formation, or is it triggered by changes in the nutrient status? How do changes in sugar production and inorganic nitrogen assimilation interact in different conditions and at different stages of the life history to determine the response of whole plant growth and allocation to elevated [CO2]?
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The influence of rising atmospheric CO2 concentrations and phosphorus nutrition on growth, grain yield and quality of a early maturing rice cultivar (Oryza sativa L. cv. Jarrah) was investigated by growing plants in a range of phosphorus levels at either 350 or 700 μL CO2 L⁻¹ in the growth chambers. Total above ground biomass and grain yield were greater at elevated CO2 concentrations and with increasing phosphorus supply. The CO2 response was evident at all but the lowest phosphorus treatments but its magnitude was greater at moderate phosphorus supplies. The increase in grain yield at high CO2 was due mainly to an enhancement of tiller number. The phosphorus concentration in the foliage was unaffected by CO2 enrichment and the critical concentration of 1.8 g kg⁻¹ dwt was the same as reported for field-grown rice. The concentration of calcium in the foliage was increased by high CO2 and the nitrogen concentration was reduced. Chemical analysis (amylose and mineral concentration) indicated that cooked rice grain from high-CO2-grown plants would be firmer and that concentrations of Zn and Fe, which are important in the diet of humans, will be lower. These results indicate that there is a need to plan for the inevitable rise in global CO2 concentrations by selecting cultivars which will be more productive and yet maintain suitable quality characteristics under elevated CO2 levels.
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For most studies involving the response of plants to future concentrations of atmospheric carbon dioxide (CO2), a current concentration of 360-370 μatm is assumed, based on recent data obtained from the Mauna Loa observatory. In the present study, average seasonal diurnal values of ambient CO2 obtained at ground level from three global locations (Australia, Japan and the USA) indicated that the average CO2 (at canopy height) can vary from over 500 μatm at night to 350 μatm during the day with average 24-h values ranging from 390 to 465 μatm. At all sites sampled, ambient CO2 rose to a maximum value during the pre-dawn period (03.00-06.00 hours); at sunrise, CO2 remained elevated for several hours before declining to a steady-state concentration between 350 and 400 μatm by mid-morning (08.00-10.00 hours). Responses of plant growth to simulations of the observed variation of in situ CO2 were compared to growth at a constant CO2 concentration in controlled environment chambers. Three diurnal patterns were used (constant 370 μatm CO2, constant 370 during the day (07.00-19.00 hours), high CO2 (500 μatm) at night; or, high CO2 (500 μatm) at night and during the early morning (07.00-09.00 hours) decreasing to 370 μatm by 10.00 hours). Three plant species - soybean (Glycine max, L (Merr.), velvetleaf (Abutilon theophrasti L.) and tomato (Lycopersicon esculentum L.) - were grown in each of these environments. For soybean, high night-time CO2 resulted in a significant increase in net assimilation rate (NAR), plant growth, leaf area and biomass relative to a constant ambient value of CO23 by 29 days after sowing. Significant increases in NAR for all three species, and significant increases in leaf area, growth and total biomass for two of the three C3 species tested (velvetleaf and soybean) were also observed after 29 days post sowing for the high night/early morning diurnal pattern of CO2. Data from these experiments suggest that the ambient CO2 concentration experienced by some plants is higher than the Mauna Loa average, and that growth of some agricultural species at in situ CO2 levels can differ significantly from the constant CO2 value used as a control in many CO2 experiments. This suggests that a reassessment of control conditions used to quantify the response of plants to future, elevated CO2 may be required.
Article
Two cultivars of spring wheat (Triticum aestivum L. cv. 'Nandu' and cv. 'Minaret') and one cultivar of spring barley (Hordeum vulgare L. cv. 'Alexis') were exposed to CO2 enrichment (concentrations ranging from 363 to 650 μl l-1), ozone (ambient and 1.7 times ambient levels) at different levels of nitrogen nutrition in open-top field chambers from sowing to maturity. CO2 increased grain yield and shoot biomass, barley showing the smallest response and wheat 'Nandu' being most responsive. The cultivars were rather insensitive to ozone, however, a decrease of thousand grain weight was observed in one of the wheat cultivars ('Minaret') at high ozone levels. In this cultivar, interactions between CO2 and ozone were observed. Elevated CO2 appeared to be protective against impairments caused by ozone. CO2 and nitrogen supply strongly interacted. CO2 fertilizing effects on grain yield of wheat 'Minaret' ranged from 22.9% at 120 kg N ha-1 to 47.4% at 330 kg N ha-1. Increase in grain yield by CO2 was accompanied with a decrease of grain nitrogen content. Grain yield increase and grain nitrogen content depression exactly compensated each other and led to constant amounts of nitrogen stored in the grains on an area unit basis independent from the applied CO2 concentration. The grain quality, assessed as nitrogen content, was severely decreased by CO2 enrichment. The regressions obtained from the data suggest that nearly twice the nitrogen supply will be required to maintain the nitrogen content in grains at the same level if CO2 concentrations rise from the current 363 μl l-1 (seasonal mean 1994) to 650 μl l-1.
Article
A possible scenario for the end of the 21st century is that the atmospheric CO2 concentration will be in the range of 510-760 mu L L(-1) and that the mean global temperature will be 1.5-4.5 degrees C higher. Further, there may be greater incidences of extreme climatic events, which together with the CO2 and temperature changes will influence development, growth and grain yield of cereals such as rice and wheat. For these C-3, plants, the driving force for the growth response to elevated CO2 is higher leaf CO2 assimilation rates (4). However, the response of A to CO2 depends on temperature with maximum absolute increases occuring at temperatures which do not cause flower abortion, while negligible increases are observed at low temperatures. At high temperatures, where A is reduced because of partial inactivation of photosynthetic enzymes, the increase in A due to CO2 enrichment is still observed. Other factors, such as changes in shoot water relations or hormone concentrations, may influence growth at elevated CO2 concentrations. Wheat and rice development is accelerated by high temperature and consequently grain yield is reduced because there is less time for radiation to be intercepted during the vegetative phase. Although high CO2 also accelerates development in rice and, to a lesser extent in wheat, the extra carbohydrate produced by increases in A results in at least a 40% increase in grain yield at temperatures which do not cause flower abortion. This is due mainly to increased tiller numbers rather than increases in the number or weight of individual grains. However, the yield enhancement due to high CO2 will not necessarily compensate for decreases in yield caused by accelerated development at high temperatures. As predicted by the response of A to high CO2, the relative increase in yield, due to rising CO2 concentrations, is smaller at lower temperatures. Elevated atmospheric CO2 may improve the tolerance of plants to heat-induced drought stress by facilitating the maintenance of cell volume and photosynthetic function in the leaves. Increased carbohydrate storage in the stems may also be an advantage during grain filling if the flag leaves senesce prematurely. However, it is unlikely that the effect of very high temperatures on newer abortion will be ameliorated by high CO2. For bread making, the quality of flour produced from grain developed at high temperatures is poorer. High CO2 may also have an effect through a reduction in the protein content of wheat grain. For rice, the amylose content of the grain, a major determinant of cooking quality is increased under elevated CO2.
Article
Increases in atmospheric carbon dioxide (CO2) concentration have stimulated interest in the response of agricultural crops to elevated levels of CO2. Several studies have addressed the response of C3 cereals to CO2, but the interactive effect of nutrient supply and CO2 on apical development and spikelet set and survival has not been investigated thoroughly. Hence, an experiment was conducted in the greenhouse to evaluate the effect of high (700 μmol CO2mol−1 air) and low (400 μmol mol−1) levels of atmospheric CO2 on apical development, spikelet set and abortion, and pre- and post-anthesis growth in spring barley (Hordeum vulgare L.) grown under high N (0.3 g N pot−1 before sowing −1–0.11 g N pot−1 week−1) and low N (0.3 g N pot−1) regimes. The plants were grown in 5 L pots. Development of spike was hastened due to CO2 enrichment, and the C+ plants pollinated few days earlier than the C— plants. Carbon dioxide enrichment had no effect on date of ripening. Development of spike slowed following application of extra N, and plants pollinated 10 days later and matured 2 weeks later when compared with plants under low N. Carbon dioxide enrichment did not affect the number of spikelets at anthesis. Excess N decreased spikelet abortion and the increased maximum number of spikelets under both [CO2]. Barley plants did not tiller when grown in low [CO2] and low N. Increased endogenous IAA concentration in those plants, recorded three days before tillers appeared in other treatments, may have contributed to this. Carbon dioxide enrichment increased the C concentration of plants, but decreased the N concentration under high N regime. Both the C and N concentration of plants were increased under high N regime. Carbon dioxide enrichment increased the total dry matter of mature plants by 9 % under high N regime and by 21 % under low N regime. Under high [CO2] increased kernel number on tiller spikes, and increased kernel weight both on main stem and on tiller spikes resulted in a 23 % increase in kernel yield under low N regime and 76 % increase in kernel yield under high N regime. The rate of N application influenced growth and yield components to a greater extent than CO2 enrichment. At maturity, plant dry matter, kernel weight, the number of kernels per spike, and the number of spikes per plant were higher under high N regime than under low N regime. Long days (16 h), low light intensity (280 μmol m−2s−1), and at constant temperature of 20 °C high [CO2] increased kernel weight and the number of kernels on tiller spikes under high and low N application rate, but did not increase the number of kernels on main stem spike, or the number of tillers or tiller spikes per plant.
Article
The rising levels of atmospheric CO2 are likely to increase biomass production of C3 species in both natural and managed ecosystems because photosynthetic rates will be higher. The greatest absolute increase in productivity will occur when nitrogen and phosphorus availability in the soil is high. Low nitrogen does not preclude a growth response to high CO2, whereas some C3 species fail to respond to high CO2 when phosphorus is low, possibly because insufficient phosphorus is available to maintain maximum photosynthetic activity at high CO2. C3 plants response to high CO2 because the flux of carbon through the photoreductive cycle is increased and photorespiration is suppressed. This change in metabolism appears to alter the foliar nutrient concentration required to promote maximum productivity (critical concentration). Higher phosphorus concentrations are needed at elevated CO2, whereas the nitrogen requirement is reduced by CO2 enrichment. Since critical concentrations are used to evaluate nutrient status of crop and forest species and to manage fertiliser programs, they will need reassessing as the atmospheric CO2 concentration rises. Another consequence of the altered nutrient requirement at high CO2 is that the nitrogen concentrations of foliage, roots and grain are consistently lower in plants grown at elevated CO2, irrespective of availability of nitrogen in the soil. In natural ecosystems, the lower nitrogen to carbon ratio of the litter may alter rates of nutrient cycling. For farmers, the rising CO2 concentrations could cause reductions in grain nitrogen, and therefore protein content. This could have important implications for baking quality of hard wheats as well as affecting the nutrient value of grain such as rice.
Article
Limitations in nutrient availability apparently can restrict plant response to COâ enrichment; however, the alterations in physiological processes associated with such restrictions have not been defined. This experiment was conducted to investigate certain physiological responses of N-limited soybean (Glycine max (L.) Merr. cv. Lee) plants growing in a COâ enriched environment and to examine their role in determining growth and yield. The nonnodulating soybean plants were grown to maturity in controlled environment chambers at 350 or 700 ..mu..L L⁻¹ COâ and at 0.05, 1.0, 2.5, 5.0, or 10.0 mM KNOâ⁻ supplied in nutrient solution. Substantial increases in whole-plant growth and seed yield occurred in both COâ treatments with increasing nitrate levels; the increases were greater, however, at high COâ. At all NOâ⁻ levels except the lowest, exposure to high COâ resulted in increased total leaf area, mean net assimilation rate, NOâ⁻ uptake, and N utilization efficiency. Increased NOâ⁻ uptake was associated with larger root systems, as uptake per unit of root mass was lower than controls. Carbon dioxide enrichment had little effect on dry matter partitioning among plant parts or harvest index. Alterations in partitioning were related to differences in NOâ⁻ supply. The results suggest that atmospheric COâ enrichment can stimulate seed yield of soybean even when the availability of N in the rhizosphere is limited.
Article
Ozone in the troposphere can cause plant stress, whereas elevated CO2 generally causes positive responses. Little is known of how these gases interact to affect plant response. Interactive effects on yield and seed quality of soybean [Glycine max (L.) Merr.] grown in 14-L pots were measured in open-top field chambers. Essex was tested in 1993, and Essex, Holladay, and NK 6955 were tested in 1994. Plants were exposed from emergence to maturity to four CO2 levels (ambient and 1.3, 1.6, and 2.0 times ambient) and three O3 levels (0.4, 0.9, and 1.5 times ambient) in 12 combinations. Increasing O3 suppressed growth and yield, whereas CO2 enrichment stimulated growth and yield. Carbon dioxide-induced stimulation was greater for plants stressed by O3 than for non stressed plants. For example, CO2 at 2.0 times ambient increased 2-yr mean seed yield of Essex by 16, 24, and 81% at O3 levels of 0.4, 0.9, and 1.5 times ambient, respectively. Effects of O3 and CO2 on seed oil content were variable with numerous cultivar differences. Seed protein content was never affected. Elevated O3 suppressed oleic acid content in seeds, whereas CO2 increased it; the nature of the O3 x CO2 interaction for oleic acid was similar to that observed for most yield measures. Carbon dioxide-induced stimulation of plants stressed by O3 was apparently caused partly by amelioration of O3 stress. Interactions between O3 and CO2 must be considered for proper interpretation of cause-effect relationships in CO2 enrichment studies.
Article
It is expected that the progressive increase of tropospheric trace gases such as COâ and Oâ will have a significant impact on agricultural production. The single and combined effects of COâ enrichment and tropospheric Oâ on grain quality characteristics in soft red winter wheat (Triticum aestivum L.) were examined in field studies using 3 m in diam. open-top chambers. Wheat cultivars {open_quotes}Massey{close_quotes} (1991) and {open_quotes}Saluda{close_quotes} (1992) were exposed to two COâ concentrations (350 vs. 500 μmol COâ mol⁻¹; 12 h d⁻¹) in combination with two Oâ regimes (charcoal-filtered air vs. ambient air + 40 ± 20 nmol Oâ mol⁻¹, 7 h d⁻¹; Monday to Friday) from late March until maturity in June. Grain quality characteristics investigated included: test weight, milling and baking quality, flour yield, protein content, softness equivalent, alkaline water retention capacity, and cookie diameter. In general, exposure of plants to either elevated COâ or weekly chronic Oâ episodes caused only small changes in grain quality. Milling and baking quality score were not significantly changed in response to treatments in both years. Flour yield was increased by elevated COâ but this increase was counteracted when elevated COâ was combined with chronic Oâ exposure. Flour protein contents were increased by enhanced Oâ under elevated COâ. Although the single effect of either COâ enrichment or chronic Oâ exposure had some impact o grain quality characteristics, it was noted that the combined effect of these gases was minor. It is likely that the concomitant increase of COâ and Oâ in the troposphere will have no significant impact on wheat grain quality. 25 refs., 1 fig., 2 tabs.
Article
Although the response of rice (Oryza sativa L.) to increasing atmospheric COâ concentration and air temperature has been examined at the greenhouse or growth chamber level, no field studies have been conducted under the tropical, irrigated conditions where the bulk of the world`s rice is grown. At the International Rice Research Institute, rice (cv. IR 72) was grown from germination until maturity for the 1994 wet and 1995 dry seasons at three different COâ concentrations (ambient, ambient + 200, and ambient + 300 μL L⁻¹) resulted in a significant increase in total plant biomass (+31%, +40%) and crop yield (+15%, + 27%) compared with the ambient control. The increase in crop yield was associated with an increase in the number of panicles per square meter and a greater percentage of filled spikelets. Simultaneous increases in COâ and air temperature did not alter the biomass at maturity (relative to elevated COâ alone), but plant development was accelerated at the higher growth temperature regardless of COâ concentration. Grain yield, however, became insensitive to COâ concentration at the higher growth temperature. Increasing both COâ and air temperature also reduced grain quality (e.g., protein content). The combination of COâ and temperature effects suggests that, in warmer regions (i.e., >34°C) where rice is grown, quantitative and qualitative changes in rice supply are possible if both COâ and air temperature continue to increase. 24 refs., 6 figs., 4 tabs.
Article
The redistribution of N from vegetative plant parts to the developing seed in soybeans [Glycine max (L.) Merrill] may influence the duration of seed filling and yield. The objective of this study was to investigate the N redistribution characteristics of soybean cultivars of varying maturities and growth habit. Eight cultivars ranging from Maturity Group II to V and including indeterminate, determinate, and semi-dwarf growth habits were grown in the field in 1977 and 1978 at Lexington, Ky. using conventional cultural practices. The soil type was a Lanton silt loam (Cumulic Haplaquolls) in 1977 and an Eagam silt loam (Cumulic Hapludolls) in 1978. Nitrogen redistribution was estimated by harvesting plants at beginning seed growth (R5) and at maturity. The abscised leaf blades and petioles were also collected and the dry weight and total N was measured in all plant parts. The vegetative dry weight at RS increased in cultivars of later maturity. There were no consistent culvar differences in N concentration at R5. The proportion of seed N that came from redistribution varied from 30 to essentially 100% and there were significant cultivar differences. The cultivar differences were positively correlated with the amount of N in the plant at R5 which was determined primarily by the vegetative dry weight at R5. Late maturing cultivars got more of their seed N from redistribution than early maturing cultivars. Although there were significant cultivar differences in yield and the duration of seed fill, they were not related to the amount of seed N that came from redistribution. Nitrogen redistribution does not appear to be an important factor determining the duration of seed filling or yield in soybeans. Please view the pdf by using the Full Text (PDF) link under 'View' to the left. Copyright © . .
Article
Spring wheat and spring barley were grown in elevated atmospheric CO2 in controlled environments. Wheat was grown in monoculture and in competition with three weed species. In monoculture, wheat had 30% more grain yield and 28% less grain nitrogen in elevated compared to ambient atmospheric CO2- In competition, wheat had no significant increase in yield with elevated atmospheric CO2- In competition, grain nitrogen concentration was reduced in response to CO2 with the largest reduction occurring with the smallest competitor and the smallest reduction occurring with the largest competitor. Spring barley was grown in monoculture at three nitrogen fertilizer supplies. In elevated atmospheric CO2 there were significant increases in grain yield and reductions in grain nitrogen concentration at all levels of nitrogen supply. In both species the reductions in grain nitrogen concentration were large enough to affect current bread making processes.
Article
The rising levels of atmospheric CO2 are likely to increase biomass production of C3 species in both natural and managed ecosystems because photosynthetic rates will be higher. The greatest absolute increase in productivity will occur when nitrogen and phosphorus availability in the soil is high. Low nitrogen does not preclude a growth response to high CO2, whereas some C3 species fail to respond to high CO2 when phosphorus is low, possibly because insufficient phosphorus is available to maintain maximum photosynthetic activity at high CO2. C3 plants response to high CO2 because the flux of carbon through the photoreductive cycle is increased and photorespiration is suppressed. This change in metabolism appears to alter the foliar nutrient concentration required to promote maximum productivity (critical concentration). Higher phosphorus concentrations are needed at elevated CO2, whereas the nitrogen requirement is reduced by CO2 enrichment. Since critical concentrations are used to evaluate nutrient status of crop and forest species and to manage fertiliser programs, they will need reassessing as the atmospheric CO2 concentration rises. Another consequence of the altered nutrient requirement at high CO2 is that the nitrogen concentrations of foliage, roots and grain are consistently lower in plants grown at elevated CO2, irrespective of availability of nitrogen in the soil. In natural ecosystems, the lower nitrogen to carbon ratio of the litter may alter rates of nutrient cycling. For farmers, the rising CO2 concentrations could cause reductions in grain nitrogen, and therefore protein content. This could have important implications for baking quality of hard wheats as well as affecting the nutrient value of grain such as rice.
Article
summaryGrain sorghum [Sorghum bicolor (L.) Moench, a C4 crop] and soybean [Glycine max (L.) Merr. cv. Stonewall, a C3 crop] plants were grown in ambient (c. 360μl 1−1) and twice-ambient (c. 720 μl 1−1) CO2 levels in open-top chambers in soil without root constriction. Plant dry mass, energy content, composition and construction cost (i.e. amount of carbohydrate required to synthesize a unit of plant dry mass) were assessed at the end of the growing season. Elevated CO2 (a) increased phytomass accumulation (kg per plant) in both species, (b) had little affect on energy concentration (MJ kg−1 plant) but caused large increases in the amount of plant energy per ground area (MJ m−2 ground), and (c) did not alter specific growth cost (kg carbohydrate kg−1 plant growth) but greatly increased growth cost per ground area (kg carbohydrate m−2 ground) because growth was enhanced. For soybean, twice-ambient CO2 resulted in a 50 % increase in the amount of nitrogen